World War I

"World War One", "Great War", and "WWI" redirect here. For other uses, see World War One (disambiguation), Great War (disambiguation), and WWI (disambiguation).

World War I
Clockwise from the top: The road to Bapaume in the aftermath of the Battle of the Somme, 1916 British Mark V tanks crossing the Hindenburg Line, 1918 HMS Irresistible sinking after hitting a mine in the Dardanelles, 1915 A British Vickers machine gun crew wearing gas masks during the Battle of the Somme, 1916 German Albatros D.III biplane fighters near Douai, France, 1917
Date 28 July 1914 – 11 November 1918 (1914-07-28 – 1918-11-11) (4 years, 3 months and 2 weeks) Peace treaties Treaty of Versailles Signed 28 June 1919 (4 years and 11 months) Treaty of Saint-Germain-en-Laye Signed 10 September 1919 (5 years, 1 month, 1 week and 6 days) Treaty of Neuilly-sur-Seine Signed 27 November 1919 (4 years, 1 month, 1 week and 6 days) Treaty of Trianon Signed 4 June 1920 (5 years, 10 months and 1 week) Treaty of Sèvres Signed 10 August 1920 (6 years, 1 week and 6 days) United States–Austria Peace Treaty Signed 24 August 1921 (3 years, 8 months, 2 weeks and 3 days) United States–Germany Peace Treaty Signed 25 August 1921 (4 years, 4 months, 2 weeks and 5 days) United States–Hungary Peace Treaty Signed 29 August 1921 (3 years, 8 months, 3 weeks and 1 day) Treaty of Lausanne Signed 24 July 1923 (8 years, 8 months, 3 weeks and 4 days) Location Europe, Africa, the Middle East, the Pacific Islands, China, Indian Ocean, North and South Atlantic Ocean Result Allied victory Central Powers victory on the Eastern Front nullified by defeat on the Western Front and Italian Front Fall of all continental empires in Europe (including Germany, Russia, Ottoman Empire and Austria-Hungary) Russian Revolution and Russian Civil War, with the collapse of the Russian Empire and the subsequent formation of the Soviet Union Widespread unrest and revolutions throughout Europe and Asia Creation of the League of Nations (see Aftermath of World War I) Territorial changes Formation of new countries in Europe and the Middle East Transfer of German colonies and territories, Partitioning the former Ottoman Empire, Austria-Hungary and the Russian Empire, transfer of territories to other countries
Belligerents
Allied Powers: France British Empire United Kingdom Canada Australia India Ceylon New Zealand Newfoundland South Africa Russian Empire (until 1917) Serbia Belgium Japan Montenegro Italy (from 1915) United States (from 1917) Romania (from 1916) Portugal (from 1916) Hejaz (from 1916) Greece (from 1917) Siam (from 1917) China (from 1917) ... and others	Central Powers: German Empire Austria-Hungary Ottoman Empire Bulgaria (from 1915) ... and others
Commanders and leaders
Raymond Poincaré Georges Clemenceau George V H. H. Asquith David Lloyd George Nicholas II † Georgy Lvov Alexander Kerensky Victor Emmanuel III Vittorio Orlando Woodrow Wilson Emperor Taishō Albert I Peter I Ferdinand I and others ...	Wilhelm II Franz Joseph I Karl I Mehmed V Mehmed VI Three Pashas Ferdinand I and others ...
Strength
Total: 42,928,000 12,000,000 8,660,000 5,839,000 5,093,000 4,744,000 1,680,000 1,234,000 800,000 707,000 629,000 417,000 380,000 230,000 200,000 136,000 129,000 50,000	Total: 25,248,000 13,250,000 7,800,000 2,998,000 1,200,000
68,176,000 (Total all)
Casualties and losses
Military dead: 5,525,000 Military wounded: 12,832,000 Total: 18,357,000 KIA, WIA and MIA Civilian dead: 4,000,000 further details ... Military deaths by country: 1,811,000 1,398,000 1,115,000 651,000 250,000–335,000 275,000 117,000 59,000–88,000 26,000 7,000 3,000 <1,000	Military dead: 4,386,000 Military wounded: 8,388,000 Total: 12,774,000 KIA, WIA and MIA Civilian dead: 3,700,000 further details ... Military deaths by country: 2,051,000 1,200,000 772,000 88,000

World War I: Mobilized forces per total population (in %)

World War I, often abbreviated as WWI or WW1, also known as the First World War or the Great War, was an international conflict that began on 28 July 1914 and ended on 11 November 1918. It involved much of Europe, as well as Russia, the United States and Turkey, and was fought in the Middle East, Africa and parts of Asia. One of the deadliest conflicts in history, an estimated 9 million were killed in combat, while over 5 million civilians died from occupation, bombardment, hunger or disease. Genocides and the 1918 Spanish flu pandemic spread by the movement of combatants during the war caused many millions of additional deaths worldwide.

In 1914, the Great Powers were divided into two opposing alliances, the Triple Entente, consisting of France, Russia, and Britain, and the Triple Alliance, made up of Germany, Austria-Hungary, and Italy. Tensions in the Balkans came to a head on 28 June 1914 following the assassination of Archduke Franz Ferdinand, the Austro-Hungarian heir, by Gavrilo Princip, a Bosnian Serb. Austria-Hungary blamed Serbia and the interlocking alliances involved the Powers in a series of diplomatic exchanges known as the July Crisis. On 28 July, Austria-Hungary declared war on Serbia; Russia came to Serbia's defence and by 4 August, the conflict had expanded to include Germany, France and Britain, along with their respective colonial empires. In November, the Ottoman Empire, Germany and Austria formed the Central Powers, while in April 1915, Italy joined Britain, France, Russia and Serbia as the Allied Powers.

Facing a war on two fronts, German strategy in 1914 was to defeat France, then shift its forces to the East and knock out Russia, commonly known as the Schlieffen Plan. This failed when their advance into France was halted at the Marne; by the end of 1914, the two sides faced each other along the Western Front, a continuous series of trench lines stretching from the Channel to Switzerland that changed little until 1917. By contrast, the Eastern Front was far more fluid, with Austria-Hungary and Russia gaining, then losing large swathes of territory. Other significant theatres included the Middle East, the Alpine Front and the Balkans, bringing Bulgaria, Romania and Greece into the war.

Shortages caused by the Allied naval blockade led Germany to initiate unrestricted submarine warfare in early 1917, bringing the previously neutral United States into the war on 6 April 1917. In Russia, the Bolsheviks seized power in the 1917 October Revolution and made peace in the March 1918 Treaty of Brest-Litovsk, freeing up large numbers of German troops. By transferring these to the Western Front, the German General Staff hoped to win a decisive victory before American reinforcements could impact the war, and launched the March 1918 German Spring Offensive. Despite initial success, it was soon halted by heavy casualties and ferocious defence; in August, the Allies launched the Hundred Days Offensive and although the German army continued to fight hard, it could no longer halt their advance.

The Central Powers began to collapse; Bulgaria signed an Armistice on 29 September, followed by the Ottomans on 31 October, then Austria-Hungary on 3 November. Isolated, facing revolution at home and an army on the verge of mutiny, Kaiser Wilhelm abdicated on 9 November and the new German government signed the Armistice of 11 November 1918, bringing the fighting to a close. The 1919 Paris Peace Conference imposed various settlements on the defeated powers, the best known being the Treaty of Versailles. The dissolution of the Russian, German, Ottoman and Austro-Hungarian empires led to numerous uprisings and the creation of independent states, including Poland, Czechoslovakia and Yugoslavia. For reasons that are still debated, failure to manage the instability that resulted from this upheaval during the Interwar period ended with the outbreak of World War II in 1939.

Names

The term world war was first coined in September 1914 by German biologist and philosopher Ernst Haeckel. He claimed that "there is no doubt that the course and character of the feared 'European War' ... will become the first world war in the full sense of the word," citing a wire service report in The Indianapolis Star on 20 September 1914.

Prior to World War II, the events of 1914–1918 were generally known as the Great War or simply the World War. In October 1914, the Canadian magazine Maclean's wrote, "Some wars name themselves. This is the Great War." Contemporary Europeans also referred to it as "the war to end war" or "the war to end all wars" due to their perception of its then-unparalleled scale and devastation. After World War II began in 1939, the terms became more standard, with British Empire historians, including Canadians, favouring "The First World War" and Americans "World War I".

Background

Main article: Causes of World War I

Political and military alliances

Rival military coalitions in 1914: Triple Entente in green; Triple Alliance in brown. Only the Triple Alliance was a formal "alliance"; the others listed were informal patterns of support.

For much of the 19th century, the major European powers maintained a tenuous balance of power among themselves, known as the Concert of Europe. After 1848, this was challenged by a variety of factors, including Britain's withdrawal into so-called splendid isolation, the decline of the Ottoman Empire and the rise of