Assassination in Sarajevo
(28 June 1914)

    On 28 June 1914, Franz-Ferdinand, Archduke of Austria and heir to the imperial throne, and his wife were assassinated during a visit to Sarajevo by Bosnian-Serb nationalists opposed to the Austrian presence.

    This assassination is seen as the event that led to the outbreak of war.

Europe plunges into war

    23 July, Austria-Hungary sent an ultimatum to Serbia, which was rejected.

    28 July, Austria-Hungary declared war on Serbia and began to bomb Belgrade.

    1 August, Germany declared war on Russia.

    3 August, Germany declared war on France.

    4 August, the German Army invaded Belgium. The United Kingdom, having guaranteed Belgium’s neutrality, declared war on Germany.


For additional information please refer to the animated map "Europe plunges into war » in our series World War I.

France’s “Sacred Union”

    The President of France, Raymond Poincaré, first used the term “Union sacrée” in a speech to the Chamber of Deputies on 4 August. He declared that, in time of war, political parties must set aside their differences and concentrate their efforts on a single objective: Victory.

    A “Sacred Union Government” was formed on 26 August.

    An equivalent concept was found in Germany: the “Burgfrieden” (The Fortress Peace).

The Battle of the Frontiers,
August 1914

    During the battles in August 1914, the German armies drove back the French and British troops, but the Allies were able to regroup.

    The French General Staff’s tactic of continuous attacks proved to be disastrous against the enemy’s artillery and led to very high casualties.

    On 22 August alone 27,000 French soldiers were killed.

Battle of Tannenberg

    The Battle of Tannenberg took place on 26-30 August in the northern region of today’s Poland.

    The German victory halted the advance movement of Russian armies towards Königsberg after their invasion of Eastern Prussia.

    A week later, Germany won a second battle near the Mazurian Lakes and ended Russia’s offensive on this front.

The 1st Battle of the Marne
(5-12 September 1914)

    Early in September, the French and British armies, which had been forced to retreat since the beginning of August, launched a violent counter-offensive on the River Marne. Disoriented by this assault, the German Army had to withdraw, thereby forestalling the threat of an invasion of France.

    But Germany’s retreat was orderly, and a new front was established along the River Aisne.


For additional information please refer to the animated map "The Battle of the Marne" in our series World War I.

The Race to the Sea

    After the Battle of the Marne, the Allied and German armies tried to go around each other’s defences by turning towards the West. This series of operations, known as the “Race to the Sea, gradually lead the opposing forces to the North Sea.

    These troop movements marked the last phase of the period of “manoeuvre warfare.” The new front was now established along a line from the coast to Switzerland and stayed in place until spring 1918.

The Ottoman Empire enters the war by joining the Central Powers
(2 November 1914)

    Although Turkey’s political leaders were divided on which side to support, the Minister of War, Enver Pasha, and his entourage admired Germany. Turkey therefore came into the war alongside the Central Powers. It officially declared war on Russia on 2 November 1914.

Manoeuvre warfare replaced by trench warfare

     Applying 19th century manoeuvre warfare strategies, the infantry and light cavalry regiments were on the front lines in military offensives and battles. However, the introduction of more effective artillery firepower caused heavy losses in the beginning of the war, and the General Staffs were forced to change tactics. Going forward, manoeuvre warfare was replaced by trench warfare.

     This phase of the war was no less deadly. When soldiers launched an assault against an enemy position, they were exposed to enemy fire, and losses were very high.

The Ottoman offensive against the Suez Canal

    Early in 1915, the Ottoman Empire launched an offensive from Palestine towards the Suez Canal. This attack was halted by the British, who then had to leave troops in the region to defend that front.

1st use of poison gas by Germany at Ypres (22 April 1915)

    British troops were the first to suffer from the use of chemical weapons.

    Disregarding international conventions on warfare adopted in The Hague between 1899 and 1907, Germany launched gas attacks against British troops at Ypres in spring 1915.

    Surprised by the use of this new weapon, the Allied Command was unprepared to protect their troops.

    The first gas masks were issued during 1915.

    The Allies also used chemical weapons.

Italy enters the war on the side of the Allies

    Both sides in the war wanted Italy as an ally and put strong pressure on the Italian government to join them.

    Prime Minister Antonio Salandra secretly signed the Treaty of London on 26 April 1915. Under the terms of this treaty, the Allies promised Italy the regions of Trentino and Trieste, which had a majority of Italian-speaking inhabitants, but were part of the Austro-Hungarian Empire.

    Italy declared war on the Austro-Hungarian Empire on 23 May 1915.

Allied troop landings in the Dardanelles
(April 1915 – January 1916)

    Early in 1915, the First Lord of the Admiralty, Winston Churchill, called for a new offensive against the Ottoman Empire.

    Following the failure of a purely naval operation in the Dardanelle Straits on 18 March, Australian and New Zealand (ANZAC), British and French troops landed to the south of the Gallipoli peninsula on 25 April. They were quickly blocked.     Another landing further north in August led to a new failure. This battle took place in terrible conditions: heat, lack of water, and dysentery.

    The order by General Staff to retreat finally arrived in December, and the evacuation was complete in early January 1916.

    Losses on both sides were very heavy.


For additional information please refer to the animated map "The Dardanelles Campaign" in our series World War I.

Armenian genocide in the Ottoman Empire

    In December 1914 and January 1915, Turkish armies were defeated by a Russian offensive in the Caucasus. The military command blamed the loss on the defection of Armenian-Turkish soldiers to the Russian army.

    This served as a pretext for the deportation and massacre of Armenians living in the Ottoman Empire.

The liner Lusitania sunk by a German submarine (7 May 1915)

    German submarines were ordered to stop merchant ships from entering the enemy’s territorial waters.

    The Lusitania, a British trans-Atlantic liner from the Cunard Line, was torpedoed off the Irish coast on 7 May. The ship was carrying gunpowder and explosives and sank very quickly. Of the 1,128 persons lost, 128 were Americans, and this caused outrage in the United States.

    Germany suspended its submarine warfare for a while.

The Zimmerwald Conference
(5-8 September 1915)

    Delegates of Socialist movements from 11 countries attended this conference, held in a small Swiss village a few kilometres from Bern.

    The conference adopted a manifesto that condemned the war and called for peace without annexation.

Bulgaria joins the Central Powers
(14 October 1915)

    Still stunned by its defeat in the 2nd Balkan War (1913) and the loss of Macedonia, Bulgaria decided to join the Central Powers.

    Its entry into the war directly contributed to the defeat of Serbia, which was being attacked from all sides.

The Serbian Army is defeated and retreats

    In October 1915, Serbia was attacked by a joint offensive from the German, Austro-Hungarian and Bulgarian armies.

    To avoid annihilation, the Serbian Army launched a difficult retreat through Albania. It was evacuated from Corfu to Salonika by the Allied navies, and incorporated into the Eastern Army.


For additional information please refer to the animated map "Serbia’s defeat 1915" in our series World War I.

Disaster at Kut-al-Amara
(16 December – 29 April)

    Three months after the beginning of the First World War, the British occupied Basra, the Ottoman Empire’s port on the Persian Gulf.

    By the end of 1915, they had moved up towards Bagdad and occupied the city of Kut-al-Amara, 390 km north of Basra, but quickly found themselves besieged by the Turkish army.

    All attempts to lift the siege failed and General Townshend, head of the British Army, was forced to surrender with all his men.

    The total losses for the British were 25,000 men, two and a half times the number of Turkish deaths.

Compulsory military service introduced in Great Britain
(24 January 1916)

    At the beginning of the war the British Army was essentially a volunteer force. As the months passed, the number of available troops decreased, which led to the British Government’s decision to introduce obligatory military service in January 1916.

Battle of Verdun
(February – December 1916)

    Germany launched an offensive against the stronghold at Verdun, but met with heavy resistance from the French Army. The battlefield around Verdun was bombarded for 300 days, receiving 60 million shells of various calibres. Losses on both sides were considerable: 160,000 French soldiers were killed and 140,000 for Germany. Nevertheless, when the battle ended, the front line had moved by only a few kilometres.

For additional information please refer to the animated map "The Battle of Verdun" in our series World War I.

The Kienthal Conference
(24-30 April 1916)

    At the height of the Battle of Verdun, delegates of socialist movements met at Kienthal in Switzerland where they launched a new appeal for an end to war.

    Despite the battle fatigue that was emerging among the belligerents, this appeal had little effect.

Naval Battle of Jutland between the German and British navies
(31 May-1 June 1916)

    Off the coast of Denmark, the British and German navies fought the most important naval battle of World War I.

    Losses were heavy on both sides; 14 ships for the British and 11 for the Germans, and thousands of lives were lost.

    Germany claimed victory, but decided against further attacks on the Royal Navy. The British suffered heavier losses, but maintained their control of the seas.

The Arab revolt against the Ottoman Empire
(June 1916)

    In order to open a new front against the Ottoman Empire, the British and French sought support from the Arabs. One of the most famous emissaries of the Allied forces was T.E. Lawrence who convinced Sherif Hussein of Mecca to rebel against the Ottoman Empire in June 1916.

Battle of the Somme
(1 July-18 November 1916)

    The British Army assumed a major role in the Somme offensive launched by the Allies.

    The first day was a disaster for the British troops with 20,000 men killed and nearly 40,000 wounded.

    The offensive rapidly degenerated into a war of attrition. By 18 November, the Allied forces had only advanced by a few kilometres, representing a major failure.

    The human cost was heavy: more than a million men died on both sides.


For additional information please refer to the animated map "The Battle of the Somme" in our series World War I.

Publication of Le Feu, a novel by Henri Barbusse
(3 August 1916)

    This memoire was first published as a serial in L’Œuvre, one of the rare daily newspapers not intimidated by French government censorship. Barbusse, a writer-journalist and committed pacifist, drew from personal notebooks to describe his daily life in the trenches. The novel was published in November 1916 and received the Prix Goncourt.

    The English translation, Under Fire, was published in the United Kingdom in 1917.

    It remains one of the masterpieces of war literature.

Romania joins the Allies
(27 August 1916)

    Romania, having remained neutral during the early phases of the war, joined the Allies in August 1916.

    Before long, the Central Powers attacked the country, and Bucharest fell in early December.

Beginning of total submarine war
(31 January 1917)

    While Germany was stalled by a very effective Allied blockade, the supporters of submarine warfare became more vocal in Berlin.

    Despite the reluctance of his Chancellor, Bethmann Hollweg, Kaiser Willhem II agreed to launch total submarine war.

    The German submarine campaign achieved spectacular results, but led to the entry of the United States in the war.


For additional information please refer to the animated map "Submarine Warfare" in our series World War I.

Revolution in Petrograd
(8-12 March 1917)

    Protests led by women demanding bread and coal were quickly followed by similar protests from workers, provoking bloody confrontations between demonstrators and soldiers.

    After 11 March, the troops joined the demonstrators, and the next day sailors also took part and occupied the Winter Palace where the government had its offices.

    Nicholas II abdicated on 15 March, the day after the members of the Duma established a provisional government.

The United States joins the Allies
(2 April 1917)

    Despite being re-elected with the slogan “He kept us out of war”, in November 1916 President Woodrow Wilson decided to enter the war against Germany.

    The new all-out German submarine offensive and the interception of a telegram from Zimmerman, Germany’s Foreign Minister, encouraging Mexico to declare war against the United States, shocked American public opinion.

    This context, together with Germany’s attempts to attack freedom of commerce, led to the United States’ entry into the war.

16 April-8 May: Chemin des Dames. Crisis and mutinies in the French Army

    Despite a few successes, French Commander-in-Chief Nivelle’s attack failed to break through Germany’s strong defensive systems.

    The terrible losses in this campaign (40,000 French soldiers killed during the first two weeks) and the demoralization of the troops led to a wave of mutinies.

    The most notable mutinies took place in May and June. The soldiers wanted an end to these bloody and futile attacks, along with a better system of home leave.

Arrival in France of General Pershing, Commander of the American Expeditionary Forces
(13 June 1917)

    General Pershing arrived at Boulogne-sur-Mer in France on 13 June 1917, followed soon after by the rest of the American Expeditionary Forces.

    From then until the end of the war, more than 2 million men, together with tons of equipment and munitions, arrived via French ports and in particular Saint-Nazaire.

Battle of Passchendaele
or the 3rd Battle of Ypres
(16 July-10 November 1917)

    This allied offensive, led by the British General Haig, involved troops from the United Kingdom, Australia, New Zealand and Canada, with reinforcements from the French Army.

    Heavy rain during the battle hindered the troops’ forward movement and forced the soldiers to fight in mud.

    This offensive lasted several months, costing many lives without any real success in breaking through the German front.

Italy defeated at Caporetto
(24 October - 9 November 1917)

    Fighting near the River Isonzo in the Alps, Italy suffered a terrible defeat two years after their entry in the war. The Italian troops had to retreat back to the River Piave, 140 km to the southwest, abandoning most of the Veneto to the Austro-Hungarian forces.

The Bolshevik Revolution in Russia (the October Revolution),
6-7 November

    Soon after his return from exile in April 1917, Lenin denounced the provisional Russian government. With Leon Trotsky, he launched a new Communist revolution. During the night of 24 October (according to the Julian calendar) the Communists took Petrograd and overthrew the provisional government.

Clemenceau becomes Prime Minister of France
(16 November)

    President Poincaré, despite his personal dislike for Clemenceau, invited him to head the French government, as France found itself in a context of defeatism and battle fatigue. Known as the ‘Tiger’ and, later, the ‘Father of Victory’, Clemenceau deployed tremendous energy to “continue the war” until victory was assured.

First massive use of tanks at Cambrais
(20 November)

    On 20 November, the British Army launched an offensive involving several hundred tanks and managed to breech the German front.

    However this offensive ended quickly, and over the next few days the Germans recaptured the territory they had lost. Nevertheless, this new weapon had proved its efficacy, and the Allies were to make greater use of tanks during the last months of the war.

President Wilson and the 14 points
(8 January 1918)

    The American President wanted to construct a new basis for international relations in order to preserve peace. His proposal containing 14 points was presented to the American Congress on 8 January 1918 and included: the right of peoples to self-determination, free international trade, even during war, and collective security guaranteed by a “League of Nations”.

Strikes in Germany
(January-April 1918)

    The winter of 1918 was particularly rigorous and, with severe food supply bottlenecks, became known as “the turnip winter”. An announcement that bread rations would be reduced was badly received and led to huge strikes in Germany’s major cities: Magdeburg, Hamburg, Leipzig, etc. 300,000 people went on strike in Berlin alone in April 1918.

The Brest-Litovsk Peace Treaty
(3 March 1918)

    The conditions for peace imposed by the Germans on Lenin were extremely harsh. Russia had to abandon all its claims on Poland, Lithuania, Finland and Ukraine.

    Russia left the war as a conquered nation and lost more than 800,000 square kilometres of its territory.

Return to manoeuvre warfare
(from March 1918)

    Following the Russian withdrawal, the German army clearly outnumbered the combined British and French forces.

    However, the German General Staff was aware that this situation was only temporary, since American soldiers were now arriving in Europe. They initiated a new series of violent offensives late in March, allowing the German Army to make some progress.

The Allies organize a unified command
(14 April 1918)

    German advances during the spring of 1918 demonstrated the necessity of better coordination among the Allied armies. General Foch was then named Allied Supreme Commander on the French front.

Bombarding of Paris by long-range cannons
(23 March- 9 August)

    Long-range German cannons (erroneously called “Big Berthas”) bombarded Paris between 23 March and 9 August, killing 256 persons and wounding 625 others.

    The shells were fired from a distance of 120 km, a feat never seen before. The worst hit was on the church of St. Gervais during Good Friday mass. Part of the roof fell on the congregation, causing the death of 88 people.

Treaty of Bucharest
(7 May 1918)

    After Russia withdrew from the war, Romania was no longer able to continue fighting against the Central Powers. Signed in the Royal Palace in Bucharest, this peace treaty led to the transfer of substantial territories to the German and Austro-Hungarian Empires. The treaty was later denounced, and the Romanians re-entered the war on 31 October.

The turning point in the war
(mid-July 1918)

    The offensive in Champagne, launched by the Germans on 15 July, led to some victories, but these were rapidly negated by a Franco-American counteroffensive three days later.

    This Allied victory marked the turning point in the war, thanks to the massive use of tanks and airplanes.

Demoralization of the German Armies

    On 8 August, for the first time since the beginning of the war, the German troops showed signs of weakness. Surprised by the Allied counteroffensive, many soldiers allowed themselves to be captured or surrendered.

    General Ludendorff called this the “collapse of our combative strength”.