World War I

World War I, also called the First World War or the Great War, was a global conflict fought from 28 July 1914 to 11 November 1918. It was between two coalitions: the Allies (or Entente) and the Central Powers. It was one of the deadliest conflicts in history, with 15 to 22 million deaths, including deaths from war crimes and genocides. The war also helped spread the Spanish flu pandemic. It brought important new weapons, including machine guns, artillery, aircraft, chemical weapons, and tanks.

The causes of World War I included the rise of the German Empire, which upset the long-standing balance of power in Europe. Rivalries between empires grew stronger, shown by new alliances and an arms race among the great powers. On 28 June 1914, tensions in the Balkans reached a breaking point when Gavrilo Princip, a Bosnian Serb, assassinated Franz Ferdinand, heir to the Austro-Hungarian throne. Austria-Hungary blamed Serbia and declared war, and the Russian Empire prepared to defend Serbia. Germany then declared war on Russia and France, and the United Kingdom joined after Germany invaded Belgium. On the Western Front, the fighting settled into long lines of trenches that stretched from the English Channel to Switzerland. The Eastern Front was more active, but neither side won a clear advantage. The Ottoman Empire joined the Central Powers, Japan and Italy joined the Allies, and a major Allied campaign at Gallipoli failed.

Huge battles at Verdun, the Somme, and Passchendaele did not break the stalemate on the Western Front. In April 1917, the United States joined the Allies after Germany resumed unrestricted submarine warfare against Atlantic shipping. Later that year, the Bolsheviks took power in Russia during the October Revolution. Soviet Russia signed an armistice with the Central Powers, then a separate peace in March 1918. That spring, Germany launched a spring offensive in the west, which had early successes but left the German Army worn out and discouraged. Beginning in August 1918, the Allied Hundred Days Offensive caused the German front line to collapse. By early November, the Allies had signed armistices with the Ottomans and with Austria-Hungary, leaving Germany alone. Facing a revolution at home, Kaiser Wilhelm II abdicated on 9 November, and the war ended with the Armistice of 11 November 1918.

The Paris Peace Conference of 1919–1920 set the terms for the defeated powers. Under the Treaty of Versailles, Germany lost large areas of land, was disarmed, and had to pay large war reparations to the Allies. The collapse of the Russian, German, Austro-Hungarian, and Ottoman empires led to new national borders and new independent countries, including Poland, Finland, the Baltic states, Czechoslovakia, and Yugoslavia. The League of Nations was created to keep world peace, but it could not manage the instability of the interwar period, which helped lead to the outbreak of World War II in 1939.

Other terms that also lead to this article include WWI (disambiguation), The First World War (disambiguation), World War One (disambiguation), and Great War (disambiguation).

Names

Before World War II, the events of 1914–1918 were commonly called the Great War or simply the World War. In August 1914, The Independent said of the conflict, "This is the Great War. It names itself." In the decade after it ended, many hoped it would be "the war to end all wars," because of its unprecedented destructiveness and death toll.

The earliest known use of the term First World War appeared in September 1914, when German biologist and philosopher Ernst Haeckel wrote that the ongoing "European War" would become "the first world war in the full sense of the word."

Background

Main article: Causes of World War I

For much of the 19th century, the major European powers kept a fragile balance of power, known as the Concert of Europe. After 1848, this was challenged by Britain's splendid isolation, the decline of the Ottoman Empire, New Imperialism, and the rise of Prussia under Otto von Bismarck. Prussia won the Franco-Prussian War in 1870–1871, which let Bismarck consolidate a German Empire. France then wanted to avenge this defeat and expand France's colonial empire. Bismarck made agreements to keep the powers from fighting each other. In 1873 he negotiated the League of the Three Emperors, which included Austria-Hungary, Russia, and Germany. After the Russo-Turkish War of 1877–1878, this league ended because Austria worried about Russian influence in the Balkans. Germany and Austria-Hungary then formed the Dual Alliance in 1879, which became the Triple Alliance when Italy joined in 1882. In 1887, Bismarck arranged a secret Reinsurance Treaty between Germany and Russia. In 1890, Wilhelm II forced Bismarck to retire. His new Chancellor, Leo von Caprivi, did not renew the Reinsurance Treaty, and France then agreed to the Franco-Russian Alliance in 1894. This was followed by the 1904 Entente Cordiale with Britain, and the Triple Entente was completed by the 1907 Anglo-Russian Convention. These were not formal alliances, but by settling longstanding colonial disputes in Asia and Africa, British support for France or Russia in a future conflict became possible. This was shown when Britain and Russia supported France against Germany during the Agadir Crisis of 1911.

Germany's economic and industrial strength kept growing quickly after 1871. Backed by Wilhelm II, Admiral Alfred von Tirpitz wanted to build an Imperial German Navy that could compete with the Royal Navy. He based this on the ideas of US naval author Alfred Thayer Mahan, who argued that a blue-water navy was vital for global power. Bismarck had opposed competing with the Royal Navy, and after his dismissal the Anglo-German naval arms race began. The launch of HMS Dreadnought in 1906 made every existing battleship out of date and gave Britain an advantage it never lost. In 1911, Chancellor Theobald von Bethmann Hollweg accepted defeat in the navy race and switched spending from the navy to the army. This was driven by German worries about Russia's recovery after the Russo-Japanese War and the 1905 Russian Revolution. Germany added 170,000 troops to its army in 1913, and France extended military service from two to three years. The years before 1914 also brought a series of crises in the Balkans, as powers sought to benefit from the Ottoman decline. Russia, which was Pan-Slavic and Orthodox, saw itself as the protector of Serbia, but it preferred the Bosporus straits to stay under a weak Ottoman government. Russia also had ambitions in northeastern Anatolia. Austria saw Serbian expansion as a threat, and in the Bosnian Crisis of 1908–1909 it annexed Bosnia and Herzegovina, which it had occupied since 1878. This happened at the same time as the Bulgarian Declaration of Independence. After the Italo-Turkish War, the Balkan League, made up of Serbia, Bulgaria, Montenegro, and Greece, overran most Ottoman territory in the Balkans during the First Balkan War. When Serbia captured ports on the Adriatic, Austria partly mobilised, including units in Galicia, but the Russian government chose not to respond. The Treaty of London in 1913 created an independent Albania, but disputes between the winners led to the Second Balkan War, in which Bulgaria lost most of Macedonia and Southern Dobruja. This mix of resentment, nationalism and insecurity helped make the Balkans known as the "powder keg of Europe."

Prelude

For a chronological guide, see Timeline of World War I.

Main article: Assassination of Archduke Franz Ferdinand

On 28 June 1914, Archduke Franz Ferdinand of Austria, heir presumptive to Emperor Franz Joseph I of Austria, visited Sarajevo, the capital of the recently annexed Bosnia and Herzegovina. Several young men from the Young Bosnia movement, including Cvjetko Popović, Gavrilo Princip, Nedeljko Čabrinović, Trifko Grabež, Vaso Čubrilović (Bosnian Serbs) and Muhamed Mehmedbašić (from the Bosniaks community), waited along the route to assassinate him. They had been given weapons by extremists in the Serbian Black Hand intelligence organisation and hoped his death would free Bosnia from Austrian rule. Čabrinović threw a grenade at the Archduke's car and injured two of his aides, and the other attempts failed. Later, when Ferdinand's car took a wrong turn, Princip fired two pistol shots, fatally wounding Ferdinand and his wife Sophie. Historian Zbyněk Zeman wrote that in Vienna the event almost made no impression, while historian Christopher Clark described it as a terrorist event that changed the political situation in Vienna.

Austro-Hungarian authorities encouraged anti-Serb riots in Sarajevo. Violence against ethnic Serbs was also organised in other cities in Bosnia and Herzegovina, Croatia and Slovenia. About 5,500 prominent Serbs were imprisoned, and a further 460 were sentenced to death. A mostly Bosniak special militia, the Schutzkorps, was set up and carried out the persecution of Serbs.

Main article: July Crisis

See also: German entry into World War I, Austro-Hungarian entry into World War I, and Russian entry into World War I

The assassination started the July Crisis, a month of diplomatic manoeuvring among Austria-Hungary, Germany, Russia, France and Britain. Austrian officials believed Serbian intelligence had helped organise the murder and saw war as the best way to end Serbian interference in Bosnia, although the Foreign Ministry had no solid proof. On 23 July, Austria gave Serbia an ultimatum with ten demands made to be unacceptable, so that Austria would have an excuse to start a war. Serbia accepted most terms but not all, and Austria broke off diplomatic relations. On 28 July, Austria declared war on Serbia and began shelling Belgrade. Russia ordered general mobilisation to support Serbia on 30 July. German Chancellor Bethmann Hollweg wanted to win backing from the SPD political opposition by presenting Russia as the aggressor, so he delayed war preparations until 31 July. The German General Staff had long expected a war on two fronts, and the Schlieffen Plan aimed to defeat France first and then turn to Russia. Once the German ultimatum to Russia expired on 1 August, the two countries were at war. Britain's cabinet was divided, but its obligations to Belgium under the Treaty of London and the support of Prime Minister Asquith and public opinion led Britain to act. French Commander-in-Chief Joseph Joffre was told not to cross into Belgium before a German invasion. On 2 August, Germany occupied Luxembourg, and on 3 August, Germany declared war on France. Germany invaded Belgium early on 4 August, and Albert I of Belgium called for help. When Britain's ultimatum demanding that Germany withdraw from Belgium expired at midnight without a response, Britain and Germany were at war.

Progress of the war

Further information: Diplomatic history of World War I

Fighting took place on many fronts. On the Western Front, Germany's advance through Belgium and France was stopped in 1914, and both sides dug into trenches. Battles such as Verdun and the Somme caused huge numbers of casualties. At sea, Britain blockaded Germany, and Germany used submarines to attack Allied ships. The United States entered the war on the Allied side in April 1917. In the Balkans, Serbia held off Austria-Hungary in 1914, but in 1915 Bulgaria joined the attack and Serbia was conquered. Italy joined the Allies in 1915 and fought Austria-Hungary along the Italian Front. Russia's armies suffered defeats, and unrest at home led to revolution in 1917. In 1918, Russia made peace with Germany, and the Allies began to push the Central Powers back.

By the autumn of 1918, the Central Powers were collapsing. Bulgaria signed an armistice on 29 September, and the Ottoman Empire surrendered on 30 October. Austria-Hungary also asked for an armistice, and Italy's army advanced to Trento, Udine, and Trieste. In Germany, sailors revolted, and a republic was declared on 9 November 1918. Germany then surrendered, and the armistice of 11 November 1918 ended the fighting.

Main article: Serbian campaign

Main articles: German invasion of Belgium (1914), Battle of the Frontiers, and Great Retreat

Main article: Asian and Pacific theatre of World War I

Main article: African theatre of World War I

Main article: Indian Army during World War I Further information: Hindu–German Conspiracy, Niedermayer–Hentig Expedition, and Third Anglo-Afghan War

Main article: Western Front (World War I)

Main article: Naval warfare of World War I

Main articles: Balkan Front (World War I), Bulgaria during World War I, Serbian campaign, and Macedonian front See also: Noemvriana

Main article: Ottoman Empire in World War I See also: Middle Eastern theatre of World War I

Main articles: Italian front (World War I), White War, and Military history of Italy during World War I

Main article: Eastern Front (World War I)

Main article: Romania in World War I For a chronological guide, see Timeline of World War I (1917–1918). Main articles: February Revolution, October Revolution, and Treaty of Brest-Litovsk

Main article: American entry into World War I Further information: Nivelle offensive and 1917 French Army mutinies

Main article: Sinai and Palestine campaign

Main article: German Caucasus expedition See also: Meuse-Argonne offensive

Main articles: Vardar offensive and Battle of Dobro Pole

Main articles: Armistice of Salonica, Armistice of Villa Giusti, and Armistice of Mudros Further information: Armistice of Belgrade

Main article: Armistice of 11 November 1918

Aftermath

Main article: Aftermath of World War I

Further information: Sykes–Picot Agreement

After the war, the German, Austro-Hungarian, Ottoman, and Russian empires had disappeared. Many nations regained their independence, and new ones were created. Four royal families fell as a result of the war: the Romanovs, the Hohenzollerns, the Habsburgs, and the Ottomans. Belgium, Serbia, and France were badly damaged, with France losing 1.4 million soldiers. Germany and Russia were similarly affected. A formal state of war lasted seven more months, until the Treaty of Versailles was signed with Germany on 28 June 1919. The US Senate did not approve the treaty, and the US did not formally end its part in the war until the Knox–Porter Resolution was signed on 2 July 1921 by President Warren G. Harding. Some war memorials mark the end of the war as 1919, when many troops returned home, but most commemorations focus on the armistice of 11 November 1918.

The Paris Peace Conference imposed a series of peace treaties on the Central Powers. The Treaty of Versailles dealt with Germany and, building on Wilson's 14th point, established the League of Nations on 28 June 1919. Germany had to accept responsibility for the losses caused by the war. This statement, Article 231, became known as the "War Guilt Clause," and many Germans felt humiliated and resentful. Austria-Hungary was split into several new countries, and Hungary lost 64% of its population. Russia lost much of its western border as Estonia, Finland, Latvia, Lithuania, and Poland became independent. After 123 years, Poland became an independent country again. The Kingdom of Serbia became the core of a new state, the Kingdom of Serbs, Croats and Slovenes, later renamed Yugoslavia. In Australia and New Zealand, the Battle of Gallipoli became their "Baptism of Fire," and Anzac Day now honors this moment. Greece later fought Turkish nationalists led by Mustafa Kemal, which led to a population exchange between the two countries under the Treaty of Lausanne.

Further information: Spanish flu

An estimated 15 to 22 million people died in World War I, and about 23 million soldiers were wounded. It is one of the deadliest conflicts in human history. Between 9 and 11 million of the dead were military personnel, and about 6 to 13 million were civilian casualties. Of the 60 million European soldiers called up between 1914 and 1918, about 8 million were killed, 7 million were permanently disabled, and 15 million were seriously injured. Diseases spread easily in the chaotic conditions of war. In 1914 alone, epidemic typhus killed 200,000 people in Serbia. From early 1918, the Spanish flu spread across the world and killed at least 17 to 25 million people. About eight million equines, mostly horses, donkeys, and mules, also died.

The German army was the first to use chemical weapons successfully, at the Second Battle of Ypres in 1915. These weapons caused about 1.3 million casualties, of which about 90,000 were fatal, and they broke the 1899 Hague Declaration Concerning Asphyxiating Gases and the 1907 Hague Convention on Land Warfare. During the war, the Ottoman Empire carried out mass deportations and killings of its Armenian population. Historians consider this genocide, and an estimated 1.5 million people died. The government of Turkey continues to deny the genocide today. Other groups were also attacked, including Anatolian and Pontic Greeks and Assyrian Christians. At least 250,000 Assyrian Christians were killed. About 8 million soldiers surrendered and were held in POW camps, and most of the prisoners were treated under the Hague Conventions.

Soldiers' experiences

About 42,928,000 people served in the Allied forces, while about 25,248,000 served in the Central Powers. British soldiers were at first volunteers, but they were increasingly conscripted. Conscription was common in most European countries but controversial in English-speaking countries. It was especially unpopular among minority groups, such as Irish Catholics in Ireland and Australia and French Catholics in Canada. In the US, conscription began in 1917. Opposition was still considerable, especially in rural areas and in the South, and the government relied mainly on conscription after only 73,000 volunteers joined out of a target of 1 million in the first six weeks of war. Veterans returning home often found they could talk about their experiences only among themselves, so they formed "veterans' associations" or "Legions."

Main articles: List of military attachés in World War I and List of military attachés and war correspondents in World War I

Military and civilian observers from every major power closely followed the war. Many were able to report on events from a position somewhat like the modern "embedded" positions within opposing land and naval forces.

Economic effects

Main articles: Economic history of World War I and Post–World War I recession

Further information: Home front during World War I and Financial crisis of 1914

The war changed families and work. With many men away fighting, women had to take jobs in great numbers, and industry needed to replace workers who had gone to war. This movement of women into industry and into traditionally male jobs helped the struggle for voting rights for women.

In every nation, the government's share of the economy grew. Britain cashed in its American railroad investments and borrowed heavily from Wall Street, while US government lending to the Allies greatly increased. After the war, the United States demanded repayment, and Britain still owed $4.4 billion in 1934. Britain also turned to its colonies, where geologist Albert Kitson found new deposits of manganese, a metal used in making weapons, in the Gold Coast. Germany was required to pay reparations, but payments were suspended in 1932 after the Great Depression had caused chaos around the world. When Adolf Hitler rose to power, the bonds and loans from the 1920s were cancelled, though writer David Andelman noted that "Refusing to pay doesn't make an agreement null and void." At the London Conference in 1953, Germany agreed to resume payments, and it made its final payment on these bonds on 3 October 2010. Australian prime minister Billy Hughes wrote to British prime minister David Lloyd George to express his regret that better terms could not be won.

Support and opposition for the war

Further information: Propaganda in World War I, British propaganda during World War I, and Propaganda and censorship in Italy during the First World War

Many people supported the war. In the Balkans, Yugoslav nationalists such as leader Ante Trumbić wanted Yugoslavs to be free from Austria-Hungary and other foreign powers and to have an independent Yugoslavia. The Yugoslav Committee, led by Trumbić, was formed in Paris in April 1915 and soon moved to London. In the Middle East, Arab nationalism grew in Ottoman lands as Turkish nationalism rose, and Arab leaders called for a pan-Arab state. In 1916, the Arab Revolt began in Ottoman-controlled areas to win independence. In East Africa, Iyasu V of Ethiopia supported the Dervish state, which was at war with the British in the Somaliland campaign. Ethiopia was close to joining the Central Powers before Iyasu was overthrown at the Battle of Segale due to Allied pressure on the Ethiopian aristocracy. Several socialist parties first backed the war in August 1914, but European socialists split along national lines and followed their countries into the war. In Italy, Italian nationalism was strongly backed by many groups. Gabriele D'Annunzio promoted Italian irredentism, and the Italian Liberal Party, led by Paolo Boselli, pushed for Italy to join the Allies. Benito Mussolini and Leonida Bissolati were militant supporters of the war among socialists. The Italian Socialist Party later opposed the war after anti-militarist protesters were killed, which led to a general strike called Red Week. Mussolini then formed the pro-war paper Il Popolo d'Italia in October 1914, with funds from Ansaldo, an armaments firm. This group later developed into the Fasci Italiani di Combattimento in 1919, the origin of fascism. On both sides, large sums were raised for soldiers, their families, and the injured. The Nail Men were a German example. Across the British Empire, many patriotic funds were set up, including the Royal Patriotic Fund Corporation, Canadian Patriotic Fund, and Queensland Patriotic Fund.

Main articles: Opposition to World War I and 1917 French Army mutinies

Many countries jailed people who spoke out against the war, including Eugene Debs in the US and Bertrand Russell in Britain. In the US, the Espionage Act of 1917 and Sedition Act of 1918 made it a federal crime to oppose military recruitment or make statements deemed "disloyal." Some nationalists opposed the war too. Most Irish people agreed to take part in 1914 and 1915, but a minority of Irish nationalists strongly opposed it. Irish nationalists and Marxists pursued independence, which led to the Easter Rising of 1916. The British government placed Ireland under martial law in response, and opposition to the war grew, leading to the Conscription Crisis of 1918. Other opposition came from conscientious objectors, some socialist and some religious, who refused to fight. In Britain, 16,000 people asked for conscientious objector status. Some, including peace activist Stephen Hobhouse, also refused alternative service and suffered years of prison, including solitary confinement. In 1917, protests spread in Russia. On 1–4 May 1917, about 100,000 workers and soldiers in Petrograd, and later in other Russian cities, led by the Bolsheviks, demonstrated with banners reading "Down with the war!" This created a crisis for the Russian Provisional Government. In Milan, Bolshevik revolutionaries organised riots in May 1917 calling for an end to the war. The army entered the city with tanks and machine guns to face the Bolsheviks and anarchists, and gained control on 23 May. Almost 50 people were killed and over 800 were arrested.

Technology

See also: Technology during World War I

World War I began as a clash of 20th-century technology and 19th-century tactics, which led to very large numbers of casualties. By the end of 1917, however, the major armies had modernised. They used the telephone, wireless communication, armoured cars, tanks (especially the prototype tank, Little Willie), and aircraft.

Both sides used several types of poison gas. It never proved to be a decisive weapon, but it became one of the most feared weapons of the war.

Artillery also changed greatly. In 1914, cannons were placed in the front line and fired directly at their targets. By 1917, indirect fire with guns, mortars, and even machine guns was common. New methods of spotting and ranging targets were used, especially aircraft and the field telephone. Fixed-wing aircraft were first used for reconnaissance and ground attack. To shoot down enemy planes, anti-aircraft guns and fighter aircraft were developed. Strategic bombers were created, mainly by the Germans and British, though the Germans also used Zeppelins. Towards the end of the war, aircraft carriers were used for the first time. In 1918, HMS Furious launched Sopwith Camels in a raid to destroy the Zeppelin hangars at Tønder.

Diplomacy

Main article: Diplomatic history of World War I

During the war, countries used talks and propaganda to build support for their side and to weaken support for their enemies. Wartime diplomacy mostly focused on five issues: propaganda campaigns; deciding and changing war goals, which became harsher as the war went on; trying to bring neutral nations (Italy, Ottoman Empire, Bulgaria, Romania) into the coalition by offering pieces of enemy land; and the Allies encouraging nationalist minority groups inside the Central Powers, especially Czechs, Poles, and Arabs.

Several peace proposals came from neutral countries, or from one side or the other, but none of them got very far.

Legacy and memory

Main articles: List of last surviving World War I veterans, Commonwealth War Graves Commission, and American Battle Monuments Commission

Memorials were built in thousands of villages and towns. Burial grounds that started near the battlefields were later moved to formal graveyards. Groups such as the Commonwealth War Graves Commission, the American Battle Monuments Commission, the German War Graves Commission, and Le Souvenir français care for these graveyards. Many also have monuments to the missing or unidentified dead, such as the Menin Gate Memorial to the Missing and the Thiepval Memorial to the Missing of the Somme. In 1915, John McCrae, a Canadian army doctor, wrote the poem In Flanders Fields as a salute to those who died in the war. It is still recited today, especially on Remembrance Day and Memorial Day.

The National World War I Museum and Memorial in Kansas City, Missouri honours all Americans who served in the war, and the Liberty Memorial was dedicated on 1 November 1921. The British government set aside substantial resources for the commemoration of the war during the period 2014 to 2018, led by the Imperial War Museum. On 3 August 2014, French President François Hollande and German President Joachim Gauck marked the centenary of Germany's declaration of war on France by laying the first stone of a memorial at Vieil Armand, known in German as Hartmannswillerkopf, for French and German soldiers killed in the war. For the centenary of the 1918 Armistice, French President Emmanuel Macron and German Chancellor Angela Merkel visited the site where the Armistice of Compiègne was signed and unveiled a plaque to reconciliation.

Main article: Historiography of World War I

Further information: Historiography of the causes of World War I

... "Strange, friend," I said, "Here is no cause to mourn." "None," said the other, "Save the undone years" ...

— Wilfred Owen, Strange Meeting, 1918

People began trying to understand the meaning and results of modern warfare during the war, and historians still work on this today. Teaching World War I is hard. Compared with World War II, it is often seen as "a wrong war fought for the wrong reasons," without a clear overall story of good versus evil. Because it has no clear heroes or villains, it is often taught by theme, using simple stereotypes that hide how complicated it was. Historian Heather Jones argues that the way historians study it was refreshed by a cultural shift in the 21st century. Scholars now ask new questions about military occupation, the radicalisation of politics, race, medical science, gender, and mental health. Historians have long debated why the war began, why the Allies won, whether generals were responsible for high casualty rates, how soldiers endured trench warfare, and how much the civilian home front supported the war effort.

Further information: Zone rouge and Iron harvest

As late as 2007, unexploded ordnance at battlefield sites such as Verdun and the Somme still posed a danger. In France and Belgium, people who find hidden unexploded weapons get help from weapons disposal units. In some places, plant life has still not recovered from the war.