Causes of the First World War

The First World War broke out in the summer of 1914, when the crisis that followed the assassination in Sarajevo turned, within five weeks, into a war between all the great powers of Europe. The assassination itself, however, was only the spark. The deeper causes were the division of the continent into two alliance camps, imperial rivalry, the arms race and rigid war plans, and the nationalisms that made the Balkans the most dangerous flashpoint in Europe. What turned a local Austro-Serbian conflict into a world war were decisions taken in Vienna, Berlin, St Petersburg, Paris and London, and historians have argued for more than a century over who bears the greatest responsibility for them.

Alliances and two camps (1879–1907)

The unification of Germany in 1871 changed the balance of power in Europe. Chancellor Otto von Bismarck sought security for the new empire by isolating France, which in the Franco-Prussian War had lost Alsace-Lorraine. After the Congress of Berlin in 1878, which set Russia against Austria-Hungary, Germany concluded the secret Dual Alliance with the Habsburg monarchy on 7 October 1879. It was a defensive alliance: it promised Austria-Hungary German help in the event of a Russian attack. On 20 May 1882 Italy joined, and the Triple Alliance was born.

France long remained isolated. That changed after Bismarck’s fall in 1890, when Germany let its secret treaty with Russia lapse. In August 1892 the general staffs of France and Russia signed a military convention, which on 4 January 1894 gained the status of an alliance treaty. The Franco-Russian Alliance was also defensive, but much more specific in military matters. It provided that if any of the Triple Alliance powers mobilised, France and Russia would immediately mobilise all their forces, so that Germany would have to fight simultaneously in the east and in the west.

Britain long kept clear of alliances. Towards the end of the Boer War, however, it abandoned “splendid isolation”: in January 1902 it concluded an alliance with Japan, and on 8 April 1904 it signed an agreement on colonial questions with France, known as the Entente Cordiale. In it France recognised Britain’s position in Egypt, and the British promised to support French ambitions in Morocco. On 31 August 1907 the government whose foreign policy was run by Edward Grey concluded an agreement with Russia on Persia, Afghanistan and Tibet. Contemporaries called the new alignment of France, Russia and Britain the Triple Entente, or simply the Entente.

The British agreements were not formal alliances and contained no military commitments. In November 1912 Grey exchanged letters with the French ambassador in which the two countries promised to consult each other in the event of a threat, but without any obligation to fight together, and he always stressed that London kept a free hand. The historian Günther Kronenbitter notes, however, that from the first Moroccan crisis onwards every serious conflict was treated as a test of the alliances’ cohesion. The fear of losing an ally narrowed the room for compromise, and blocs designed to be defensive made the crisis harder to contain in July 1914.

Imperialism and great-power rivalry

The second group of causes is bound up with the age of imperialism. The American historian Samuel R. Williamson writes that imperialism shaped almost every aspect of international politics in 1898–1914. In 1898 the Reichstag passed the first navy law of Admiral Alfred von Tirpitz, and Kaiser Wilhelm II proclaimed a “world policy”. Germany, Europe’s second-largest economy, demanded “a place in the sun” and seized the Chinese port of Kiaochow. In the same year, on the upper Nile at Fashoda, British and French troops came close to a clash.

Paradoxically, it was colonial disputes that brought old rivals together. After Fashoda the French foreign minister Théophile Delcassé gave up the struggle over Egypt and turned to Morocco. The agreements of 1904 and 1907 were in essence deals on spheres of influence in Africa and Asia, and the settlement with Russia, as Williamson stresses, grew out of imperial interests rather than hostility to Germany. In Berlin, however, they were seen as encirclement. Tirpitz’s naval programme was meant to force Britain to reckon with Germany, but in reality it pushed Britain towards an understanding with France and Russia.

The rivalry was not confined to distant colonies. In September 1911 Italy declared war on the Ottoman Empire to seize Tripolitania (the Italo-Turkish War). Turkey’s weakness encouraged the Balkan states to wage a war of their own, and Russia, whose grain exports passed through the Black Sea straits, objected at the end of 1913 to the dispatch of a German military mission under General Otto Liman von Sanders to Constantinople. Williamson concludes that imperialism had by then reached the European continent itself.

Crises that did not end in war

The first serious trial of strength came in Morocco. As France began to bring the country under its control, Berlin decided to remind it of its international obligations and, in passing, to test the Entente Cordiale. On 31 March 1905 Wilhelm II landed at Tangier and assured the sultan of German support. The first Moroccan crisis (PL) had begun. The French prime minister dropped Delcassé and agreed to an international conference, but the Algeciras conference in early 1906 brought Germany no gains at all. Britain and France drew even closer, and in late December 1905 their general staffs began secret talks.

The most dangerous was the Bosnian crisis. In 1908 Austria-Hungary announced the annexation of Bosnia and Herzegovina, which it had administered since 1878. The foreign minister Alois von Aehrenthal had agreed this in advance with his Russian counterpart Alexander Izvolsky, in return for support for Russian demands over the Straits, but the deal quickly fell apart and the two men accused each other of treachery. In March 1909, after a firm threat from Berlin, St Petersburg persuaded Serbia to back down. Russia suffered a humiliation, and Williamson calls the crisis a kind of prelude to July 1914.

In the spring of 1911 French troops entered Fez. On 1 July Germany responded by sending the gunboat Panther to the Moroccan port of Agadir. The second Moroccan crisis ended in November: Germany gave way in return for extensive territory in the French Congo, which was seen at home as yet another defeat. London publicly backed France, British and French staff officers drew up detailed plans for moving the British army to the Continent, and Joseph Joffre became head of the French general staff.

Each of these crises ended without war. In 1909 peace was saved by the weakness of the Russian army after its defeat by Japan, by the merely token support France and Britain gave Russia, and by the fact that Vienna did not want war. Yet the crises left lasting grievances. Wilhelm II, whom nationalists and some of his generals reproached for giving way, vowed that next time he would not back down.

The arms race and war plans

From 1898 Germany built a fleet meant to challenge the supremacy of Britain’s Royal Navy. Tirpitz’s second navy law of 1900 doubled the number of battleships. The answer of the First Sea Lord, John Fisher, was HMS Dreadnought, launched in 1906: the first fast battleship armed only with heavy guns, which made all older battleships obsolete. The race began afresh. By 1914 Britain had completed or begun another twenty-three dreadnoughts and seven battlecruisers, and Germany fifteen dreadnoughts and six battlecruisers. The mission of the British minister Richard Haldane to Berlin in 1912 brought no agreement, because Germany demanded a promise of British neutrality in return.

After 1911 the land arms race came to the fore. In 1912–1913 Germany passed major army expansion laws. France responded in 1913 by extending military service to three years, which, according to the historian Eric Dorn Brose, increased its army by almost 40 per cent, to 850,000 men in 1914, against 811,000 in the German army. Russia, whose strategic railways were financed by French banks, adopted the “Great Programme” in June 1914, which by 1917 was to enlarge its peacetime army by 45 per cent, to 1,885,000 men. In the summer of 1912 Austria-Hungary agreed to enlarge its army for the first time since 1889.

Armaments went hand in hand with war plans that relied on a swift first strike. The chief of the German General Staff, Alfred von Schlieffen, in a memorandum of December 1905, envisaged that in a two-front war Germany would first crush France, outflanking its heavily fortified border through Belgium and Holland, and only then turn against Russia. His successor Helmuth von Moltke dropped the march through Holland, and in 1913 work on a separate plan for a war against Russia alone was abandoned. From then on any war with Russia meant an immediate German attack on France through Belgium. For the German General Staff, which relied on the Schlieffen Plan, every day of Russian mobilisation shortened the time available to carry it out, which in the July Crisis made mobilisation a step almost equivalent to war.

Historians now argue whether the “Schlieffen Plan” existed in the form described after the war. The American historian Terence Zuber saw the 1905 memorandum as an attempt to extract extra troops from the War Ministry, but his conclusions have not won wide acceptance. The other side also thought in offensive terms: France prepared a thrust into Alsace and Lorraine, which in August opened the Battle of the Frontiers, and Paris pressed Russia to speed up its mobilisation and threaten Germany sooner from the east. In Berlin and Vienna the conviction grew that time was on the Entente’s side. As early as 8 December 1912, at a conference with the Kaiser, Moltke said that war was unavoidable, “the sooner the better”.

Nationalism and the Balkans

Nationalism was a force that particularly threatened multinational Austria-Hungary. In 1903 a bloody coup in Belgrade overthrew the Obrenović dynasty and brought Peter I Karađorđević to the throne. Serbia’s relations with the monarchy soon deteriorated, down to the “Pig War” over imports of Serbian pork. Serbian and South Slav nationalists dreamed of a common state of the South Slavs that would also include Bosnia. After the Bosnian crisis Serbia undertook to curb its propaganda, but did not keep its word. In 1911 officers grouped around Major Dragutin Dimitrijević founded the secret organisation Black Hand, which sought to unite the South Slavs by any means.

In Vienna Serbia had long been seen as a mortal threat, because it encouraged South Slav nationalism and undermined the loyalty of the Slavs within the monarchy. The chief of the General Staff, Franz Conrad von Hötzendorf, demanded a preventive war again and again from 1906 onwards. According to the British historian Hew Strachan, in 1913 alone he proposed war with Serbia twenty-five times. Nationalism was at work elsewhere too: many Italian circles demanded Trentino and Trieste, Romania quarrelled with Hungary over the fate of the Romanians in Transylvania, in France the memory of lost Alsace and Lorraine was still alive, and in Russia the Pan-Slavists called for the defence of the Balkan Slavs.

The greatest shock came with the Balkan Wars of 1912–1913. With the support of Russian diplomacy, Serbia, Bulgaria and Greece formed the secret Balkan League, which Montenegro also joined. On 8 October Montenegro declared war on Turkey, and the other allies soon followed. The Balkan armies drove the Turks out of large parts of Macedonia and Albania. At the end of June 1913 Bulgaria, dissatisfied with its share of the spoils, attacked its former allies and lost. Serbia nearly doubled its territory.

The Balkan Wars nearly drew in the great powers. In the winter of 1912–1913 Austria-Hungary and Russia reinforced their troops on the frontiers, and Vienna considered war three times. Peace was saved by the conference of ambassadors in London chaired by Grey, which created Albania and cut Serbia off from the sea, and by Berlin’s restraint of its ally. When in October 1913 Vienna gave Serbia a seven-day ultimatum to leave territory assigned to Albania, Belgrade gave way. Williamson notes that the Austrians drew a single lesson from this: the threat of force works. That conviction shaped their policy eight months later.

The Sarajevo assassination and the July Crisis

On 28 June 1914 in Sarajevo Gavrilo Princip, a nineteen-year-old Bosnian Serb linked to Young Bosnia, shot dead the heir to the Austro-Hungarian throne, Archduke Franz Ferdinand, and his wife Sophie. The assassins had received weapons and help in crossing the border from men connected with the Black Hand and Serbian military intelligence. It is much harder to prove that the Serbian government as a whole planned the attack, and what Prime Minister Nikola Pašić knew is still disputed. In Vienna, however, the decision began to ripen to use the assassination to settle accounts with Serbia.

First Vienna made sure of Berlin’s position. On 5 July at Potsdam Wilhelm II promised Austria-Hungary full support, even if the reckoning with Serbia led to a conflict with Russia, and the next day Chancellor Theobald von Bethmann Hollweg confirmed this “blank cheque”. The chancellor hoped that a swift strike would keep the war confined to the Balkans, since Russia was not yet ready, but he himself called this policy “a leap in the dark”. On 14 July Vienna settled on a hard line when the Hungarian prime minister István Tisza, until then an opponent of a rash war, gave way, and on 19 July the council of ministers approved the draft ultimatum.

The ultimatum was delivered in Belgrade on 23 July, only after the visit of the French president Raymond Poincaré to Russia had ended. It gave Serbia 48 hours and contained demands that infringed its sovereignty, above all the participation of Austro-Hungarian officials in an investigation on Serbian soil. On 25 July Belgrade accepted most of the points, rejecting precisely that one, but Vienna broke off diplomatic relations. Even Wilhelm II later judged that the Serbian reply had removed any reason for war. Grey proposed mediation by four powers and then a conference of ambassadors, which France and Italy accepted but Germany rejected.

On 28 July Austria-Hungary declared war on Serbia, and that same night the first shells fell on Belgrade. Wilhelm II suggested that the Austrians should occupy only Belgrade as a pledge, but the chancellor passed this proposal on to Vienna late and in a watered-down form. Russia would not allow Serbia to be destroyed. On 29 July it announced a partial mobilisation against Austria-Hungary, and the next day Tsar Nicholas II, persuaded by his foreign minister Sergei Sazonov, agreed to general mobilisation. On 31 July Berlin sent an ultimatum to Russia demanding that it halt mobilisation, and Austria-Hungary ordered general mobilisation.

On 1 August Germany mobilised and declared war on Russia, and France ordered mobilisation too. Italy held that the Triple Alliance, a defensive pact, did not oblige it to take part in the war, and declared neutrality. In line with its war plan, on 2 August Germany demanded that Belgium allow its troops through, and on 3 August it declared war on France. The same day Grey argued in the House of Commons that Britain could not stand aside. On 4 August German troops entered Belgium, whose neutrality was guaranteed by the Treaty of London of 1839. London sent Germany an ultimatum, and when it expired, Britain entered the war. Within a week of the declaration of war on Serbia, the conflict had engulfed all the great powers of Europe except Italy.

Whose fault? The historians’ debate

The argument over responsibility began before the first shots were fired. Every government presented its own steps as defensive, and foreign ministries hastily published selections of diplomatic documents. The victors settled the matter in the Treaty of Versailles, signed on 28 June 1919. Article 231 stated that Germany accepted the responsibility of herself and her allies for all the loss and damage suffered by the Allied powers as a consequence of the war imposed upon them by the aggression of Germany and her allies.

The article was intended above all to provide a legal basis for reparations, but the German foreign minister Ulrich von Brockdorff-Rantzau called it the “war guilt clause”. The German Foreign Office set up a special section to fight it and funded journals and lectures abroad. Socialists saw things differently: for Lenin and the Bolsheviks the war was a product of imperialism, and after taking power in Russia they published incriminating documents from tsarist diplomacy. By the late 1920s historians, drawing on great editions of documents, began to gain some distance, and after 1945 the prevailing view in West Germany was that the war had been caused by the anarchy of the international system and by militarism, not by any particular German guilt.

The breakthrough came in the early 1960s from the Hamburg historian Fritz Fischer. In “Griff nach der Weltmacht” and later works he argued that from the war council of December 1912 Germany’s elites had planned a war of aggression, and that during the war they sought hegemony in Europe. In his view this policy sprang from the empire’s internal problems, and Germany’s isolation was “self-encirclement”, the result of its own threats over Morocco and the Balkans. Conservative historians, led by Gerhard Ritter, accused him of a biased reading of the sources, but by the 1970s Fischer’s thesis had become the new orthodoxy.

The centenary of the outbreak of war brought a new wave of research. Christopher Clark, in his 2012 book “The Sleepwalkers”, asked not why Europe went to war but how it got there. He showed that decisions were taken simultaneously in many capitals, in states where power was dispersed, and that their effects often ran counter to their authors’ intentions. He was critical of the Russian mobilisations and of the conduct of Poincaré and Grey, and his book, especially popular in Germany, is often read as a reply to Fischer. Thomas Otte, in his study of the July Crisis, puts more stress on the recklessness of the statesmen in Vienna and Berlin. Both agree, however, that no single state or individual should bear the main burden of responsibility.

There is still no single answer. Many scholars stress that Austria-Hungary deliberately chose war with Serbia, and that Germany made almost no attempt to restrain it until the end of July. The American historian Konrad Jarausch described Bethmann’s policy as a “calculated risk” that got out of control. Others, such as Sean McMeekin, blame Russia and Sazonov for mobilising too early, and Kronenbitter points out that France, and in the end Britain too, underwrote Russia’s strategy of escalation. One thing is certain: the assassination in Sarajevo created a crisis, but it was the great powers that turned it into a general war.