I INTRODUCTION World War I, military conflict, from 1914 to 1918, that began as a local European war between Austria-Hungary and Serbia on July 28, 1914; was transformed into a general European struggle by Germany's declaration of war against Russia on August 1, 1914; and eventually became a global war involving 32 nations. Twenty-eight of these nations, known as the Allies and the Associated Powers, and including Great Britain, France, Russia, Italy, and the United States, opposed the coalition known as the Central Powers, consisting of Germany, Austria-Hungary, Turkey, and Bulgaria. The immediate cause of the war between Austria-Hungary and Serbia was the assassination on June 28, 1914, at Sarajevo in Bosnia (then part of the Austro-Hungarian Empire; now in Bosnia and Herzegovina), of Archduke Francis Ferdinand, heir-presumptive to the Austrian and Hungarian thrones, by Gavrilo Princip, a Serb nationalist. The fundamental causes of the conflict, however, were rooted deeply in the European history of the previous century, particularly in the political and economic policies that prevailed on the Continent after 1871, the year that marked the emergence of Germany as a great world power. CAUSES OF THE WAR A Nationalism B Imperialism C Military Expansion Statesmen everywhere realized that the tremendous and ever-growing expenditures for armament would in time lead either to national bankruptcy or to war, and they made several efforts for worldwide disarmament, notably at the Hague Conferences of 1899 and 1907. International rivalry was, however, too far advanced to permit any progress towards disarmament at these conferences. The European nations not only armed themselves for purposes of “self-defence”, but also, in order not to find themselves standing alone if war did break out, sought alliances with other powers. The result was a phenomenon that in itself greatly increased the chances for generalized war: the grouping of the great European powers into two hostile military alliances, the Triple Alliance of Germany, Austria-Hungary, and Italy and the Triple Entente of Great Britain, France, and Russia. Shifts within these alliances added to the building sense of crisis. D 1905-1914: Crises Foreshadowing the War MILITARY OPERATIONS A Diplomatic Moves B Declarations of War C 1914-1915: Entrenchment C1 The Western Front In the First Battle of the Marne, which took place on September 6-9, the French halted the advance of Kluck's army, which had outdistanced the other two German armies and could not obtain their support. In addition, the German forces had been weakened on August 25 when, believing the victory had already been won in the west, the German chief of staff, General Helmuth von Moltke, dispatched six corps to the eastern front. The French pressure on the German right flank caused the retreat of Kluck's army and then a general retreat of all the German forces to the River Aisne. The French advanced and, in an endeavour to force the Germans from the Aisne, engaged them in three battles: the Battle of the Aisne; a battle on the River Somme; and the First Battle of Arras. The Germans, however, could not be dislodged, and even extended their line eastwards to the Meuse north of Verdun. A race to the North Sea ensued between the two belligerents, the objective being the channel ports. The Germans were prevented from advancing to the French channel ports chiefly by the flooding of the region of the River Yser by the Belgians. The western part of the Allied line was held by the British who, in the race for the channel, had advanced to Ypres, the south-west corner of Belgium. After taking Antwerp on October 10, the Germans endeavoured to break through the British positions in Belgium, but were checked in a series of engagements known collectively as the Battle of Flanders. In December the Allies attacked along the entire front, from Nieuport in the west to Verdun in the east, but failed to make any appreciable gains. The Battle of Flanders marked the conclusion of the war of movement or fighting in the open on the western front. From the end of 1914 until nearly the end of the war in 1918, the fighting consisted largely of trench warfare, in which each side laid siege to the other's system of trenches, consisting of numerous parallel lines of intercommunicating trenches protected by lines of barbed wire, and endeavoured from time to time to break through the lines. In this type of fighting during 1915 in the west, the Allies were on the offensive; the Germans, who were engaged in a heavy offensive on the eastern front (see below), made only a single attack in the west during the year. The principal attempts in 1915 to force a breakthrough included a British attack at Neuve Chapelle in March, which took only the German advance line. The Germans unsuccessfully attacked Ypres in April, using clouds of chlorine gas, the first time in history that gas warfare was used in this manner on a large scale. A combined attack by the British and French along the front between Neuve Chapelle and Arras, in May and June, advanced troops 4 km (2.5 mi) into the German trench system, but did not secure a breakthrough. Unsuccessful simultaneous attacks were made in September by the British in the town of Lens and French at Vimy Ridge overlooking the town. A large-scale French attack in September on a front of about 25 km (15 mi) between Reims and the Argonne Forest, took the Germans' first line of trenches, but was stopped at the second. On the whole the lines that had been established in the west at the close of 1914 remained practically unchanged during 1915. C2 The Eastern Front C3 The War in Serbia On the Serbian front considerable activity took place in 1914-1915. In 1914 the Austrians undertook three invasions of Serbia, all of which were repulsed; the Serbs, however, made no attempt to invade Austria-Hungary. The front remained inactive until October 1915. Early that month, in anticipation of Bulgarian entrance into the war on the side of the Central Powers, and in order to aid Serbia, which would be the target of a Bulgarian attack, British and French troops were landed at Salonica, the gateway into the Balkans, by arrangement with the neutral Greek government. After Bulgaria declared war on Serbia on October 14, 1915, the Allied troops advanced into Serbia. The Bulgarian troops defeated Serbian forces in Serbia and also the British and French troops that had come up from Salonica. Also in anticipation of the Bulgarian declaration of war, on October 6 a strong Austro-German drive, commanded by General August von Mackensen, was launched from Austria-Hungary into Serbia. By the end of 1915 the Central Powers had conquered all of Serbia and eliminated the Serbian army as a fighting force. The surviving Serbian troops took refuge in Montenegro, Albania, and the Greek island of Corfu (Kérkira), which the French occupied in January 1916 in order to provide a place of safety for the routed Serbs. The British and French troops in Serbia retreated to Salonica, which they fortified and where they were held in readiness for later action. C4 The Turkish Front In the Mesopotamian Valley, meanwhile, British forces from India defeated the Turks in several battles during 1914-1915, particularly that of Kut-al-Imara; but in the Battle of Ctesiphon, November 1915, the Turks checked the advance of the British towards Baghdad and forced them to retreat to Kut-al-Imara. On December 7 the Turks laid siege to this town. C5 The Italian Front D 1916: Continued Stalemate German success in 1915 in thrusting the Russians back from East Prussia, Galicia, and Poland enabled Germany to transfer some 500,000 men from the eastern to the western front for an attempt to force a decision in the west during 1916. D1 Verdun and the Somme D2 Russian Losses—Romanian Defeat On the eastern front in 1916 the Russians staged an offensive in the Lake Narocz region about 95 km (60 mi) north-east of Vilna. Their attack, designed to force the Germans to move troops from Verdun to the Lake Narocz region, was a complete failure. Not only did it fail to divert the Germans in any degree from their attack on Verdun, but also the Russians lost more than 100,000 men. In June the Russians carried out a more successful offensive. In response to an Italian request for action to relieve the pressure of an Austrian offensive in the Trentino-Alto Adige region (see below), the Russians moved against the Austrians on a front extending from Pinsk south to Czernowitz. By September, when strong German reinforcements from the western front stopped the Russian advance, the Russians had driven some 65 km (40 mi) into the Austro-German position along the entire front and had taken about 500,000 prisoners. They did not succeed, however, in capturing either of their objectives, the cities of Kovel and Lemberg; and their losses of approximately 1 million men left the army in a demoralized and discouraged state. The Russian drive had nonetheless given sufficient evidence of strength to play a large part in inducing Romania to enter the war on the side of the Allies (August 27, 1916). After its entrance into the war, Romania at once began an invasion of the Austro-Hungarian province of Transylvania (August-September), but Austro-German forces speedily drove the Romanians out of that region. In conjunction with Bulgarian and Turkish troops, the Austro-German forces invaded Romania (November-December). By the middle of January 1917 Romania had been completely conquered, and the Central Powers had gained a valuable source of wheat and oil. D3 Italy and the Balkans On the Italian front 1916 was marked by another inconclusive battle on the Isonzo River, the fifth of a series in that region, and by an Austrian offensive in the Trentino designed to break through the Italian lines and reach the rear of the Italian position on the Isonzo. The Austrians gained considerable territory in the Trentino, but lacked the strength to accomplish a breakthrough, and an Italian counter-offensive (June-July) succeeded in regaining most of the captured terrain. From August to November four additional inconclusive battles took place on the Isonzo; the principal gain on either side was the capture of Gorizia by the Italians on August 9. In the Balkans during 1916 the Allied powers interfered in Greek affairs on the grounds that the Greek government under King Constantine I was, in spite of its declared neutrality, unduly favouring the Central Powers. Allied intervention brought about the establishment (September 29) of a provisional Greek government under the statesman Eleutherios Venizelos, who had consistently favoured the Allied cause. At Salonica the provisional government declared war on Germany and Bulgaria on November 3. The government of King Constantine was still in power in Athens and large parts of Greece, and friction took place between that government and the Allies, who resorted to a naval blockade of Greece and other action in order to enforce their demands that the Greeks cease aiding the Central Powers. On December 19 Great Britain officially recognized the provisional Greek government. Two periods of fighting took place in the Balkans during 1916. In August a Serbian army, brought to Salonica after having been reconstituted at Corfu, advanced together with Russian and Italian troops against the Bulgarians and Germans on the Salonica front. After they had gained some initial successes, a strong counter-attack thrust them back. Beginning in early October Allied forces began a large-scale offensive in Macedonia. On November 19 the Allied troops captured Monastir, and by the middle of December had reached Lake Ohrid, on the border of Albania and Macedonia. D4 The Turkish Dominions Considerable military activity took place in 1916 in three parts of the Turkish Ottoman Empire: Mesopotamia, Arabia, and Palestine. In Mesopotamia, the besieged town of Kut-al-Imara fell to the Turks on April 29, 1916. In December of that year the British began a drive towards the town, which they recaptured two months later. In Arabia in June 1916 Husein ibn Ali, grand sharif of Mecca, continued the traditional conflict between Arabs and Turks by leading, with his son Abdullah ibn Husein, the revolt of Al Ḩijaz (now in Saudi Arabia) against Turkish rule. Husein had the help of the British, who recognized him as king of Al Ḩijaz in December 1916. As a diversionary move to aid the Arabian revolt, the British in November began an advance from Egypt, which they had garrisoned since early in the war, into the Sinai Peninsula and Palestine, and by the early days of January 1917 had taken several fortifications. D5 Negotiation Attempts In 1916 President Woodrow Wilson of the United States, at that time a neutral nation, attempted to bring about negotiations between the belligerent groups of powers that would in his own words bring “peace without victory”. As a result of his efforts, and particularly of the conferences held in Europe during the year by Wilson's confidential adviser, Colonel Edward M. House, with leading European statesmen, some progress was at first apparently made towards bringing an end to the war. In December the German government informed the United States that the Central Powers were prepared to undertake peace negotiations. When the United States informed the Allies, Great Britain rejected the German advances for two reasons: Germany had not laid down any specific terms for peace; and the military situation at the time (Romania had just been conquered by the Central Powers) was so favourable to the Central Powers that no acceptable terms could reasonably be expected from them. Wilson continued his mediatory efforts, calling on the belligerents to specify the terms on which they would make peace. He finally succeeded in eliciting concrete terms from each group, but they proved irreconcilable. E 1917: US Entrance—Russian Withdrawal E1 Arras and Ypres The second great Allied offensive took place in June, when the British under Haig made an attempt in Flanders to break through the right wing of the German position. A preliminary battle at Messines set the stage for the main attacks (July 31-November 10) at Ypres, the so-called Third Battle of Ypres or Passchendale campaign. Desperate fighting, in which each side suffered approximately 250,000 casualties, did not result in a breakthrough. E2 Use of Tanks Other attacks of Allied forces on the western front in 1917 included a battle at Verdun, in which the French succeeded in regaining an additional section of the area they had lost the previous year; and (November 20-December 3) the Battle of Cambrai, during which the British opened the attack with a raid by nearly 400 tanks. This was the first tank raid on such a scale in military history, and, but for lack of reserves, the British might have achieved a breakthrough. As it was, the British drove an 8-km (5-mi) salient into the German lines. German counter-attacks, however, compelled the British to yield most of the newly won ground. After the United States entered the war in April 1917, it moved rapidly to raise and transport overseas a strong military force, known as the American Expeditionary Force (AEF), under the command of General John J. Pershing. By June 1917 more than 175,000 American troops were training in France, and one division was actually in the lines of the Allied sector near Belfort; by November 1918 the strength of the AEF was nearly 2 million. From the spring of 1918 US troops played an important part in the fighting. E3 Submarine Warfare E4 Russia Withdraws On the eastern front the dominating influence on the fighting during 1917 was the outbreak in March of the Russian popular uprising against the imperial government, which resulted in turn in the establishment of a provisional government and the abdication, in March, of Tsar Nicholas II. The provisional government continued the prosecution of the war, in July, under General Aleksey Alekeseyevich Brusilov, the Russians staged a moderately successful 2-week drive on the Galician front, but then lost much of the territory they had gained. In September the Germans took Riga, defended by Russian forces under General Lavr Georgiyevich Kornilov, and in October occupied the greater part of Latvia and a number of Russian-held islands in the Baltic Sea. The Bolshevik party seized power by force on November 7. A cardinal policy of Bolshevism was the withdrawal of Russia from the war, and on November 20 the government that had just come into power offered the German government an armistice. On December 15 an armistice was signed between the Russian and Austro-German negotiators, and fighting ceased on the eastern front. E5 Italian Setbacks E6 Greece Enters the War On the Balkan front in 1917, after the Allied troops had fought several inconclusive engagements at Monastir, at Lake Presba, and on the Vardar River, the Allies initiated an effort to oust the Greek king, Constantine, claiming that his pro-German sympathies and his aid to the Central Powers made it impossible for the Allies to conduct successful operations in the Balkan region. In June the Allies began an invasion of Greece, and at the same time exerted diplomatic pressure on Constantine to abdicate. He did so on June 12; Venizelos became premier of the government formed under Alexander, the son of Constantine; and on June 27 the Greek government declared war on all four Central Powers. E7 The Middle East In Palestine during 1917 the British made two unsuccessful attempts (March and April) to take the city of Gaza. Under a new commander, General (later Field Marshal) Sir Edmund Allenby, the British broke through the Turkish lines at Beersheba (November), compelling the evacuation of Gaza; and on December 9, Allenby's troops took Jerusalem. The year also witnessed the beginning of the brilliant leadership of British Colonel T. E. Lawrence, known as Lawrence of Arabia, in the Arab revolt against Turkey. Arab troops led by Lawrence took the Turkish-held port of Al'Aqabah in July, and during the remainder of the year executed many forays against the Turkish-held Hejaz railway. The year 1917 was also marked by British successes in Mesopotamia; they took Baghdad in March and by September had advanced to Ramadi on the River Euphrates and Tikrit on the Tigris. F 1918: The Final Year The early part of 1918 did not look propitious for the Allied nations. On March 3 Russia signed the Treaty of Brest-Litovsk, which put a formal end to the war between that nation and the Central Powers on terms more favourable to the latter; and on May 7 Romania made peace with the Central Powers, signing the Treaty of Bucharest, by the terms of which it ceded the Dobruja region to Bulgaria and the passes in the Carpathian Mountains to Austria-Hungary, and gave Germany a long-term lease on the Romanian oil wells. F1 Bulgaria and Austria-Hungary Withdraw On the Balkan front, however, the result of the fighting of 1918 was disastrous to the Central Powers. In September a force of about 700,000 Allied troops, consisting of French, British, Greeks, Serbs, and Italians, began a large-scale offensive against the German, Austrian, and Bulgarian troops in Serbia. The Allied offensive was so successful that by the end of the month the Bulgarians were thoroughly beaten and concluded an armistice with the Allies. The German success in Romania was nullified in November when, with the support of Allied troops who had advanced into Romania after the Bulgarian capitulation, Romania re-entered the war on the Allied side. After the conclusion of the Bulgarian armistice, the Serbian part of the Allied army continued to advance, occupying Belgrade on November 1, while the Italian army invaded and occupied Albania. On the Italian-Austro-Hungarian front, the Austrians, in June, attacked on the Piave and succeeded in crossing the river, only to be driven back with the loss of about 100,000 men. In October-November the Allies definitely gained the victory in Italy, routing the Austrians in an offensive that culminated in the Battle of Vittorio Veneto (October 24-November 4). The Allies completely shattered the Austrian army in this campaign; they took several hundred thousand prisoners and the remainder of the Austrian army fled into Austria. On November 3 the Italians at last took Trieste, and on November 5 they occupied Fiume. The shock of the defeat precipitated revolutionary events in Austria-Hungary. The Czechs and the Slovaks had already set up a separate state; in October the South Slavs proclaimed their independence, and in December set up an independent kingdom, later part of Yugoslavia (now Croatia, Slovenia, Bosnia and Herzegovina, Macedonia, and Yugoslavia). In November the Hungarians established an independent government. The Austro-Hungarian government at Vienna concluded an armistice with the Allies on November 3 and nine days later the last Habsburg emperor, Charles I, abdicated; on the following day the Austrian Republic was proclaimed. F2 Turkey Withdraws During 1918 the Allies also brought the campaigning in Palestine to a successful conclusion. In September the British forces broke through the Turkish lines at Megiddo and routed the Turkish army and the German corps that was assisting it; after being joined by Arab forces under Lawrence, the British took Lebanon and Syria. In October they captured Damascus, Aleppo, and other key points, while French naval forces occupied Beirut, and the Turkish government asked for an armistice. An armistice was concluded on October 30, and by its terms the Turks were obliged to demobilize, break relations with the Central Powers, and permit Allied warships to pass through the Dardanelles. F3 Last German Efforts Despite the German victories over Russia and Romania in 1917, at the outset of 1918 the Allies, principally through their spokesman Woodrow Wilson, formulated war aims drastically opposed to those already stated by the Central Powers; Wilson's peace policy was enunciated in an address to the US Congress and comprised 14 points designed to bring about a just peace, which were of considerable influence in inducing the Central Powers to cease hostilities later in the year. At the beginning of 1918 the Germans, realizing that victory by means of submarine warfare was impossible, and that they must force a decision on the western front before American troops might take up positions there in force, planned for the spring of the year an all-out effort to break through the Allied lines and reach Paris. The opening drive of their powerful offensive, which began on March 21, was directed at the British front south of Arras. The drive hurled the British lines back 65 km (40 mi) before it was halted, on April 5, principally by hastily summoned French reserves. The fear of a German breakthrough aroused among the Allies by the German success in the first week of the offensive caused the Allies to appoint General (later Marshal) Ferdinand Foch in charge of assuring coordination of Allied operations; in the following month he was made commander in chief of the Allied armies—French, Belgian, British, and American—in France. During April a second German thrust took Messines Ridge and Armentičres from the British, and in June a powerful German surprise attack against the French on the Aisne drove a salient 65 km (40 mi) deep into the French position and enabled the Germans to reach a point of the Marne only 60 km (37 mi) from Paris. During this battle American troops first went into action in force; together with French troops, the US Second Division halted (June 4) the German advance in the Battle of Chateau-Thierry. The Germans made additional gains of terrain in June, but by the middle of July the force of their offensive had largely been spent. In the Second Battle of the Marne, they succeeded in crossing the river, but once they were across their progress was halted by French and American troops. Sensing that the German drive had lost its power, General Foch on July 18 ordered a counter-attack. The attack drove the Germans back over the Marne, and the Allies took the initiative on the western front that they retained to the end of the war. F4 End of the War in Europe G Colonial Warfare The forces in the German colonies of Africa and the Pacific, with the chief exception of those in German East Africa in late 1917 and 1918, generally fought on the defensive. They were in some cases swiftly overcome, and in others gradually, but by the end of the war in 1918 practically all had capitulated to the Allies. G1 Africa In 1914 the German colonies in Africa consisted of Togoland, the Cameroons (German, Kamerun), German South West Africa (Nambia), and German East Africa. An Anglo-French force took possession of Togoland in August 1914. In September of that year a British force invaded the Cameroons from Nigeria, and a French force invaded from French Equatorial Africa to the east and south of the Cameroons. After many campaigns in which the Germans several times defeated the Allied forces, German resistance was finally overcome in February 1916. German South West Africa was conquered, between September 1914 and July 1915, by troops from the Union of South Africa. The most important of the German possessions, German East Africa, displayed the strongest resistance to the attacks of the Allies. Early assaults by British and Indian troops (November 1914) were repulsed by the Germans under General Paul von Lettow-Vorbeck. In November 1915, British naval units gained control of Lake Tanganyika, and the following year the Allied forces (British, South Africans, and Portuguese) intended for the invasion of German East Africa were placed under the command of General Jan Christiaan Smuts. In 1916 the Allies captured the principal towns of German East Africa, including Tanga, Bagamoyo, Dar es Salaam, and Tabora, and Lettow-Vorbeck's troops then retreated into the south-east section of the colony. Late in 1917, however, the German forces took the offensive, invading Portuguese East Africa; and in November 1918 they began an invasion of Rhodesia. When the armistice was signed in Europe in 1918, the troops in German East Africa were still fighting, even though most of the colony was in the hands of the Allies. Lettow-Vorbeck surrendered three days after the European armistice was declared. G2 The Pacific In the Pacific a force from New Zealand captured the German-held portions of Samoa in August 1914 and in September, Australian forces occupied German possessions in the Bismarck Archipelago and New Guinea. Japanese forces took the fortress of Qingdao (Tsingtao), a German-held port in Shandong (Shan-tung) Province, China, in November 1914, and between August and November of that year took possession of the German-held Marshall Islands, the Mariana Islands, the Palau group of islands, and the Caroline Islands. After the war ended, Japan retained Qingdao until 1922, and received a mandate over the Marshall Islands, many of the Marianas (including Saipan), and over the Palau group and the Carolines. H The War at Sea H1 Early Operations The year 1915 was notable for the submarine blockade Germany instituted around Great Britain. The sinking by German submarine action of the British passenger liner Lusitania on May 7 caused the loss of many American lives, leading to a controversy between the United States and Germany that almost precipitated war between the two nations. The firm stand taken by the United States forced Germany to modify its method of submarine warfare to the satisfaction of the American government. In March 1916, however, the German sinking in the English Channel by submarine of the French steamer Sussex, with the loss of American lives, led to another controversy between Germany and the United States, a virtual US ultimatum compelling Germany temporarily to cease its unrestricted submarine warfare. H2 1916 and After H3 German Fleet Scuttled The total tonnage of Allied ships sunk by German submarines, surface craft, and mines was nearly 13 million; the largest tonnage sunk in any one year was about 6 million, in 1917. I The War in the Air World War I provided a great stimulus to the production and military use of aircraft, including the aeroplane and airship, or dirigible balloon, and the tethered balloon, the evolution of air warfare, and the tethered balloon. Aircraft were used for two principal purposes: observation and bombing. For observation of stationary battlefronts extensive use was made by both belligerents of small tethered balloons; for scouting at sea, dirigible balloons were extensively used, and aeroplanes were used for scouting coastal waters. In connection with military operations on land, aeroplanes were used to observe the disposition of the troops and defences of the enemy and for bombing the enemy's lines or troops in action. A special feature of the war was the raids conducted by means of dirigibles or aeroplanes on important enemy centres far removed from the battlefront. The first German aeroplane raid on Paris took place on August 30, 1914; and the first German air raid on England was on Dover on December 21, 1914. During 1915 and 1916 the German type of dirigible known as the zeppelin raided eastern England and London 60 times. The first German aeroplane raid on London took place on November 28, 1916, and such raids were frequent during the remainder of the war. The object of the German raids on England was to bring about withdrawal of British planes from the western front for the defence of the homeland; to handicap British industry; and to destroy the morale of the civilian population. The raids caused much loss of life and damage to property but accomplished little of military value. From the middle of 1915 aerial combats between planes or squadrons of planes of the belligerents were common. The Germans had superiority in the air on the western front from about October 1915 to July 1916, when the supremacy passed to the British. Allied supremacy gradually increased thereafter and with the entrance of the United States into the war became overwhelming. In April 1918 the United States had three air squadrons at the front; by November 1918 it had 45 squadrons comprising nearly 800 planes and more than 1,200 officers. The total personnel of the American air service increased from about 1,200 at the outbreak of the war to nearly 200,000 at the end. Among the noted aeroplane fighters, or aces, were the American Eddie Rickenbacker, the Canadian William Avery Bishop, and the German Baron Manfred von Richthofen.
The underlying causes of World War I were the spirit of intense nationalism that permeated Europe throughout the 19th and into the 20th century, the political and economic rivalry among the nations, and the establishment and maintenance in Europe after 1871 of large armaments and of two hostile military alliances.
The French Revolution and the Napoleonic Wars had spread throughout most of Europe the idea of political democracy, with the resulting idea that people of the same ethnic origin, language, and political ideals had the right to independent states. The principle of national self-determination, however, was largely ignored by the dynastic and reactionary forces that dominated in the settlement of European affairs at the Congress of Vienna in 1815. Several peoples who desired national autonomy were made subject to local dynasts or to other nations. Notable examples were the German people, whom the Congress of Vienna left divided into numerous duchies, principalities, and kingdoms; Italy, also left divided into many parts, some of which were under foreign control; and the Flemish- and French-speaking Belgians of the Austrian Netherlands, whom the congress placed under Dutch rule. Revolutions and strong nationalistic movements during the 19th century succeeded in nullifying much of the reactionary and anti-nationalist work of the congress. Belgium won its independence from the Netherlands in 1830, the unification of Italy was accomplished in 1861, and that of Germany in 1871. At the close of the century, however, the problem of nationalism was still unresolved in other areas of Europe, resulting in tensions both within the regions involved and between various European nations. One particularly prominent nationalistic movement, Pan-Slavism, figured heavily in the events preceding the war.
The spirit of nationalism was also manifest in economic conflict. The Industrial Revolution, which took place in Great Britain at the end of the 18th century, followed in France in the early 19th century, and then in Germany after 1870, caused an immense increase in the manufactures of each country and a consequent need for foreign markets. The principal field for the European policies of economic expansion was Africa, and on that continent colonial interests frequently clashed. Several times between 1898 and 1914 the economic rivalry in Africa between France and Great Britain, and between Germany on one side and France and Great Britain on the other, almost precipitated a European war.
As a result of such tensions, between 1871 and 1914 the nations of Europe adopted domestic measures and foreign policies that in turn steadily increased the danger of war. Convinced that their interests were threatened, they maintained large standing armies, which they constantly replenished and augmented by peacetime conscription. At the same time, they increased the size of their navies. The naval expansion was intensely competitive. Great Britain, influenced by the expansion of the German navy begun in 1900 and by the events of the Russo-Japanese War, developed its fleet under the direction of Admiral Sir John Fisher. The war between Russia and Japan had proved the efficacy of long-range naval guns, and the British accordingly developed the widely copied dreadnought battleship, notable for its heavy armament. Developments in other areas of military technology and organization led to the dominance of general staffs with precisely formulated plans for mobilization and attack, often in programmes that could not be reversed once begun.
With Europe divided into two hostile camps, any disturbance of the existing political or military situation in Europe, Africa, or elsewhere provoked an international incident. Between 1905 and 1914 several international crises and two local wars occurred, all of which threatened to bring about a general European War. The first crisis occurred over Morocco, where Germany intervened in 1905-1906 to support Moroccan independence against French encroachment. France threatened war against Germany, but the crisis was finally settled by an international conference at Algeciras, Spain, in 1906. Another crisis took place in the Balkans in 1908 over the annexation by Austria-Hungary of Bosnia and Herzegovina. Because one form of pan-Slavism was a Pan-Serbian or Greater Serbia movement in Serbia, which had as one of its objects the acquisition by Serbia of the southern part of Bosnia, the Serbs threatened war against Austria. War was avoided only because Serbia could not fight without Russian support, and Russia at the time was unprepared for war. A third crisis, again in Morocco, occurred in 1911 when the German government sent a warship to Agadir in protest against French efforts to secure supremacy in Morocco. After threats of war on both sides, the matter was settled by a colonial compromise between France and Germany in November 1911. Taking advantage of the preoccupation of the Great Powers with the Moroccan question, Italy declared war on Turkey in 1911, hoping to annex the Tripoli region of northern Africa. Because Germany's policy of Drang nach Osten (“drive towards the East”) obliged it to cultivate friendship with Turkey, the Italian attack had the effect of weakening the Triple Alliance and encouraging its enemies. The Balkan Wars of 1912-1913 resulted in an increased desire on the part of Serbia to obtain the parts of Austria-Hungary inhabited by Slavic peoples, strengthened Austro-Hungarian suspicion of Serbia, and left Bulgaria and Turkey, both defeated in the wars, with a desire for revenge. Germany, disappointed because Turkey had been deprived of its European territory by the Balkan Wars, increased the size of its army. France responded by increasing peacetime military service from two to three years. Following the example of these nations, all the others of Europe in 1913 and 1914 spent huge sums for military preparedness.
On a Europe thus heavily armed and torn by national rivalries, the assassination of the Austrian archduke had a catastrophic effect.
The Austro-Hungarian government, considering the assassination the work of the Greater Serbian movement, concluded that the movement must be suppressed by a military expedition into Serbia. Otherwise it might become powerful enough, particularly if aided by similar movements elsewhere, to cause the disruption of the Austro-Hungarian Empire. On July 23 Austria-Hungary sent an ultimatum to Serbia submitting ten specific demands, most of which had to do with the suppression, with Austrian help, of anti-Austrian propaganda in Serbia. Urged by both Great Britain and Russia, Serbia on July 25 accepted all but two of the demands, but Austria declared the Serbian reply to be unsatisfactory. The Russians then attempted to persuade Austria to modify the terms of the ultimatum, declaring that if Austria marched on Serbia, Russia would mobilize against Austria. A proposal, on July 26, by the British foreign secretary, Sir Edward Grey, that a conference of Great Britain, France, Germany, and Italy settle the Austro-Serbian dispute, was rejected by Germany.
On July 28 Austria declared war against Serbia, either because it felt Russia would not actually fight for Serbia, or because it was prepared to risk a general European conflict in order to put an end to the Greater Serbia movement. Russia responded by partially mobilizing against Austria. Germany warned Russia that continued mobilization would entail war with Germany, and it made Austria agree to discuss with Russia possible modification of the ultimatum to Serbia. Germany insisted, however, that Russia immediately demobilize. Russia declined to do so, and on August 1 Germany declared war on Russia.
The French began to mobilize on the same day; on August 2 German troops traversed Luxembourg and on August 3 Germany declared war on France. On August 2 the German government informed the government of Belgium of its intention to march on France through Belgium in order, as it claimed, to forestall an attack on Germany by French troops marching through Belgium. The Belgian government refused to permit the passage of German troops and called on the signatories of the Treaty of 1839, which guaranteed the neutrality of Belgium in case of a conflict in which Great Britain, France, and Germany were involved, to observe their guarantee. Great Britain, one of the signatories, on August 4 sent an ultimatum to Germany demanding that Belgian neutrality be respected; when Germany refused, Britain declared war on it the same day. Italy remained neutral until May 23, 1915, when, to satisfy its claims against Austria, it broke with the Triple Alliance and declared war on Austria-Hungary. In September 1914 Allied unity was made stronger by the Pact of London, signed by France, Great Britain, and Russia. As the war progressed, other countries, including Turkey, Japan, the United States, and other nations of the western hemisphere, were drawn into the conflict. Japan, which had made an alliance with Great Britain in 1902, declared war on Germany on August 23, 1914. The United States declared war on Germany on April 6, 1917.
Military operations began on three major European fronts: the western, or Franco-Belgian; the eastern, or Russian; and the southern, or Serbian. In November 1914 Turkey entered the war on the side of the Central Powers, and fighting also took place between Turkey and Great Britain at the Dardanelles and in Turkish-held Mesopotamia. In late 1915 two more fronts had been established: the Austro-Italian, after Italy joined the Allies in May 1915; and one on the Greek border north of Salonica (Thessaloníki), after Bulgaria joined the Central Powers in October 1915.
The initial German plan of the campaign was to defeat France quickly in the west, while a small part of the German army and the entire Austro-Hungarian army held in check an expected Russian invasion in the east. The speedy defeat of France was to be accomplished by a strategic plan known as the Schlieffen plan, which had been drawn up by Count Alfred von Schlieffen, German chief of staff from 1891 to 1907. The Schlieffen plan called for powerful German forces to sweep through Belgium, outflank the French by their rapid movement, then wheel about, surround, and destroy them. As executed with certain modifications in the autumn of 1914, the plan at first seemed likely to succeed. The swift German incursion into Belgium at the beginning of August routed the Belgian army, which abandoned the strongholds of Ličge and Namur and took safety in the fortress of Antwerp. The Germans, rushing onward, then defeated the French at Charleroi and the British Expeditionary Force of 90,000 men at Mons, causing the entire Allied line in Belgium to retreat. At the same time the Germans drove the French out of Lorraine, which they had briefly invaded, and back from the borders of Luxembourg. The British and French hastily fell back to the River Marne, but three German armies advanced steadily to the Marne, which they then crossed. The fall of the French capital seemed so imminent that the French government moved to Bordeaux. After the Germans had crossed the Marne, however, the French under General Joseph Jacques Césaire Joffre wheeled around Paris and attacked the First German Army, commanded by General Alexander von Kluck, on the right of the three German armies moving on Paris.
By the end of 1914 both sides had established lines extending about 800 km (about 500 mi) from Switzerland to the North Sea and had entrenched; these lines were destined to remain almost stationary for the next three years.
On the eastern front, in accordance with the plans of the Allies, the Russians assumed the offensive at the very beginning of the war. In August 1914 two Russian armies advanced into East Prussia, and four Russian armies invaded the Austrian province of Galicia. In East Prussia a series of Russian victories against numerically inferior German forces had made the evacuation of that region by the Germans imminent, when a reinforced German army commanded by General Paul von Hindenburg decisively defeated the Russians in the Battle of Tannenberg, fought on August 26-30, 1914. The four Russian armies invading Austria advanced steadily through Galicia; they took Przemysl and Bukovina, and by the end of March 1915 were in a position to move into Hungary. In April, however, a combined German and Austrian army drove the Russians back from the Carpathians. In May the Austro-German armies began a great offensive in central Poland, and by September 1915 had driven the Russians out of Poland, Lithuania, and Courland, and had also taken possession of all the frontier fortresses of Russia. To meet this offensive the Russians withdrew their forces from Galicia. The Russian lines, when the German drive had ceased, lay behind the Dvina River between Riga and Dvinsk (Daugavpils), and then ran south to the Dnestr River. Although the Central Powers did not force a decision on the eastern front in 1914-1915, the Russians lost so many men and such large quantities of supplies that they were subsequently unable to play any decisive role in the war. In addition to the Battle of Tannenberg, notable battles on this front during 1914-1915, centred on Masuria were the First Battle of the Masurian Lakes (September 7-14, 1914), and the Second Battle of the Masurian Lakes (February 7-21, 1915), both German victories.
Turkey entered the war on October 29, 1914, when Turkish warships cooperated with German warships in a naval bombardment of Russian Black Sea ports; Russia formally declared war on Turkey on November 2, and Great Britain and France followed suit on November 5. In December the Turks began an invasion of the Russian Caucasus region. The invasion was successful at its inception, but by August 1915 the hold that Turkish forces had gained had been considerably reduced. Turkish pressure in the area, however, impelled the Russian government early in 1915 to demand a diversionary attack by Great Britain on Turkey. In response, British naval forces under the command of General Sir Ian Hamilton bombarded the Turkish forts at the Dardanelles in February 1915, and between April and August, two landings of Allied troops took place on the Gallipoli Peninsula, one of British, Australian, and French troops in April, and one of several additional British divisions in August. The Allied purpose was to take the Dardanelles; however, strong resistance by Turkish troops and bad generalship on the part of the Allied command made the Gallipoli campaign a complete failure. The Allied troops were withdrawn in December 1915 and January 1916.
Italy declared war on Austria-Hungary on May 23, 1915. The chief military events on the Austro-Italian Front in 1915 were four indecisive battles between Austro-Hungarian and Italian armies on the Isonzo River (June 29-July 7, July 18-August 10, October 18-November 3, and November 10-December 10). The purpose of the Italian attack was to break through the Austrian lines and capture Trieste.
The German plan, as worked out by Erich von Falkenhayn, chief of the general staff of the German army, was to attack the French fortress at Verdun in great strength in an effort to weaken the French irretrievably by causing the maximum possible number of casualties. The Allied plan for 1916, as laid out by commanders in chief, Marshal Joffre of the French army and General Sir Douglas Haig of the British, was to attempt to break through the German lines in the west by a massive offensive during the summer in the region of the River Somme. The Germans opened the Battle of Verdun, on February 21. After bitter fighting the Germans took Fort Douaumont (February 25), Fort Vaux (June 2), and the fortifications of Thiaumont (June 23), but did not succeed in capturing Verdun. (It was here that General Henri Philippe Pétain gained prominence as the “hero of Verdun”.) Because of the severe losses in the battle, the French were able to contribute to the Allied offensive on the Somme only 16 divisions of the 40 originally planned; the offensive, which began on July 1 and continued until the middle of November, consequently was largely in the hands of the British. They succeeded in winning about 325 sq km (125 sq mi) of territory, but the drive did not bring about a breakthrough. The First Battle of the Somme marked the earliest use of the modern tank, deployed by the British on September 15 in an attack near Courcelette. From October to December the French staged a counter-attack at Verdun and succeeded in recapturing Forts Douaumont and Vaux (November 2), restoring the situation that had prevailed before February. In August Hindenburg replaced Falkenhayn as German chief of staff with General Erich Ludendorff. In December General Robert Georges Nivelle succeeded Joffre as commander in chief of the French armies in the north and north-east.
Wilson still attempted to find some basis of agreement between the two belligerent groups until a change in German war policy in January 1917 completely altered his point of view towards the war. In that month Germany announced that, beginning on February 1, it would resort to unrestricted submarine warfare against the shipping of Great Britain and all shipping to Great Britain. German military and civil experts had calculated that such warfare would bring about the defeat of Great Britain in six months. Because the United States had already expressed its strong opposition to unrestricted submarine warfare, which, it claimed, violated its rights as a neutral, and had even threatened to break relations with Germany over the issue, Wilson dropped his peacemaking efforts. On February 3, the United States broke diplomatic relations with Germany and at Wilson's request a number of Latin American nations, including Peru, Bolivia, and Brazil, also did so. On April 6 the United States declared war on Germany.
In 1917 the Allies made two large-scale attempts to break the German lines on the western front. The first Allied attempt took place near Arras between April 9 and May 21. While it was being planned by the British and the French high commands, the Germans withdrew from their original line along the Aisne to a new position, previously prepared somewhat to the north, and known as the Hindenburg line, against which the Allies directed their attack. Their offensive included the Third Battle of Arras, in which Canadian troops captured the heavily fortified and stubbornly defended Vimy Ridge, and the British forces made an advance of 6 km (4 mi); and a battle on the Aisne, and one in the Champagne district, both of which resulted in a slight French gain at a cost in casualties so great as to cause a mutiny among the troops. Because of the failure of his reckless attack, General Nivelle on May 15 was replaced by General Henri Philippe Pétain; the new commander's policy was to remain on the defensive until US troops arrived.
In 1917 not only did the United States enter the war, but also the Germans failed in their attempt to drive Great Britain to surrender through the destruction by submarine of the British and Allied shipping on which it depended for food and other supplies. At the outset the German submarine campaign seemed likely to succeed. Towards the end of 1916 German submarines were destroying monthly about 300,000 tons of British and Allied shipping in the North Atlantic; in April 1917 the figure was 875,000 tons. Because the Germans had calculated that the destruction of 600,000 tons monthly for six consecutive months would be sufficient to force Great Britain to capitulate, they were doubly certain of victory after April. Great Britain, however, roused itself to unprecedented efforts to fight the submarine menace. By the adoption of a convoy system of screening fleets of merchant vessels with warships, especially destroyers and submarine chasers, and by the use of hydroplanes for spotting submarines and depth charges for destroying them, Great Britain, as the summer advanced, rendered the German submarine campaign less and less effective. By the autumn, although large numbers of Allied ships were still being sunk, the Germans were sustaining heavy losses in submarines. At the same time the Allied nations, especially the United States, were rapidly building new shipping. By the outset of 1918 the Allies were turning out more new ships than the Germans were destroying, and the German effort to end the war by submarine warfare had clearly failed.
The Allies suffered disaster on the Italian front in 1917. During the first eight months of the year, despite deficiencies in troop strength, artillery, and ammunition, the Italian forces under General Luigi Cadorna continued efforts to break through the Austrian lines on the Isonzo River and to attain Trieste. The Italian drives of 1917, which resulted in the 10th and 11th battles of the Isonzo, did not attain their objective. The latter part of the year (October-December) was marked by a determined Austro-German offensive carried on by nine Austrian and six newly arrived German divisions. Attacking on the upper Isonzo near the town of Caporetto, they succeeded in breaking the line of the Italians, who fell back in confusion from the Isonzo to positions on the Piave River. In the disastrous Battle of Caporetto the Italian forces lost 300,000 men as prisoners alone and, the morale of the army broken, approximately the same number as deserters. In November British and French troops arrived to reinforce the Italians on the Piave, and a new Italian commander in chief, General Armando Díaz, was appointed in place of General Cadorna.
Beginning with a British drive (August 8-11) into the German lines around Amiens, the Allies began the offensive that three months later resulted in German capitulation. During the last week of August and the first three days of September, British and French forces won the Second Battle of the Somme and the Fifth Battle of Arras, and drove the Germans back to the Hindenburg line. A particularly strong German salient was then reduced by American troops (September 12-13) in the Battle of Saint-Mihiel, and more than 14,000 prisoners were taken. In October and early November the British moved towards Cambrai and the Americans advanced partly through the Argonne Forest. The latter thrust broke the German lines between Metz and Sedan. As a result of these offensives, Ludendorff requested his government to seek an armistice with the Allies. The German government initiated armistice talks (October) with the Allies, but they failed when President Wilson insisted on negotiating only with democratic governments. The British advance meanwhile made rapid progress in northern France and along the Belgian coast, and on November 10, US and French troops reached Sedan. By the beginning of November the Hindenburg line had been completely broken, and Germans were in rapid retreat on the entire western front. The defeat of the German army had domestic political repercussions that were catastrophic to the established German government. The German fleet mutinied; an uprising dethroned the king of Bavaria; and in November Emperor William II abdicated and fled to the Netherlands. The German republic was proclaimed on November 9. An armistice commission had already been dispatched to negotiate with the Allies. At 5 a.m. on November 11, an armistice was signed in the Forest of Compičgne between Germany and the Allies on terms laid down by the Allies; at 11 the same morning hostilities ended on the western front.
At the outset of war the main British fleet, the Grand Fleet, consisted of 20 dreadnoughts and numerous other ships, including battle cruisers, cruisers, and destroyers; and the Grand Fleet was based principally at Scapa Flow, in the Orkney Islands north of Scotland. A second British fleet, consisting of older ships, was used to guard the English Channel. The German fleet, the High Seas Fleet, consisting of 13 dreadnoughts, was based on the North Sea ports of Germany.
During 1914 no major naval engagements between the belligerents took place in the Atlantic. In the Battle of Helogland Bight, the British raided the German naval base at Helgoland, an island off Germany in the North Sea, sinking three German ships. German submarines sunk several British naval units, including the superdreadnought Audacious (October 27); and a daring attempt by German submarines to raid Scapa Flow caused the British naval units stationed there to withdraw to bases on the west coast of Scotland.
In the South Pacific a squadron of German cruisers under the command of Admiral Maximilian von Spee did considerable damage to installations at the French island of Papeete and the British-held Fanning Island (September and October 1914); defeated a British squadron off the headland of Coronel, Chile (November 1) in the Battle of Coronel; and on December 8 was defeated with the loss of four out of its five ships in the Battle of Falkland Islands by a British squadron under Admiral Sir Frederick Sturdee. During 1914 and the early part of 1915 German cruisers did considerable damage to British shipping in the Indian Ocean and elsewhere until captured or otherwise put out of commission.
The most important naval engagement of the war was the Battle of Jutland, waged on May 31 and June 1, 1916, between the British Grand Fleet and the German High Seas Fleet. Although the British losses, both in ships and human lives, were greater than Germany's, the German fleet, having returned to home ports, did not venture to give battle again during the war, and the British retained their supremacy at sea. Nevertheless, during the remainder of the war, German cruisers managed to run the blockade of Germany, which the British had established from the outset of the war. The Germans sank considerable tonnage of Allied shipping in the North Atlantic and then returned to their bases. In 1917 the Germans again resorted to unrestricted submarine warfare, convinced that this method was the only one that would defeat Great Britain. The plan not only failed to force the capitulation of Great Britain, but also caused the United States to declare war against Germany. The attacks of German submarines on British convoys in the Atlantic and in the North Sea caused much loss of shipping. As a result, in April 1918 the British attempted to block the German submarine bases at Ostend (Oostende) and Zeebrugge in Belgium; they succeeded in partially blocking Zeebrugge by sinking three overage British cruisers in the harbour, but failed at Ostend. In October, however, British land forces, advancing through Belgium, took the two submarine bases and other Belgian ports.
By the terms of the armistice the Germans surrendered to the Allies most of their fleet, consisting of 10 battleships, 17 cruisers, 50 torpedo boats, and more than 100 submarines. All of the fleet with the exception of the submarines was interned at Scapa Flow in November 1918, with German captains and crews aboard. The Treaty of Versailles (1919), which ended the war, provided that all the interned ships become the permanent property of the Allies; that other warships still in German possession also be surrendered; and that the size of any future German navy be drastically limited. In reprisal against these terms, the Germans on June 21, 1919, scuttled their ships interned at Scapa Flow.
World War I began on July 28, 1914, with the declaration of war by Austria-Hungary on Serbia, and hostilities between the Allied and Central Powers continued until the signing of the armistice on November 11, 1918, a period of 4 years, 3 months, and 14 days. The aggregate direct war costs of all the belligerents amounted to about US$186 billion. Casualties in the land forces amounted to more than 37 million (see the accompanying table, World War I Casualties); in addition, close to 10 million deaths among the civilian populations were caused indirectly by the war. Despite worldwide hopes that the settlements arrived at after the war would restore world peace on a permanent basis, World War I actually provided the basis for an even more devastating conflict. The defeated Central Powers declared their acceptance of President Wilson's 14 points as the basis for the armistice and expected the Allies to utilize the principles of the 14 points as the foundation for the peace treaties. On the whole, however, the Allies came to the conference at Versailles and to the subsequent peace conferences with the determination to exact from the Central Powers reparations equal to the entire cost of the war, and to distribute among themselves territories and possessions of the defeated nations according to formulae arrived at secretly during the years 1915 to 1917, before the entry of the United States into the war. President Wilson, in the peace negotiations, at first insisted that the Paris Peace Conference accept the full programme laid out in the 14 points, but finally, in order to secure the support of the Allies for the all-important 14th point, which called for the creation of the League of Nations, he abandoned his insistence on some of the other points.
The peace treaties that emerged from the conferences at Versailles, Saint-Germain, Trianon, Neuilly, and Sčvres were on the whole inadequately enforced by the victorious powers, leading to the resurgence of militarism and aggressive nationalism in Germany and to social disorder throughout much of Europe.
