In 1915, on the Western Front, there are several attempts by the Allies to break the deadlock. However, these prove futile as Germans are well entrenched in their defense. Both sides realize that it would be difficult to break the stalemate on the Western Front. On the Eastern Front, the Germans are successful against the Russians forcing them to retreat. As Italy joins World War I on May 23, 1915 on the side of the Allies, a new front is opened along the border between Austria-Hungary and Italy. The major events of the First World War in 1915 also include the Gallipoli Campaign; the first large scale use of poison gas; the beginning of the Armenian Genocide in the Ottoman Empire; and the sinking of Lusitania. Here is a timeline of events of World War I which took place in 1915
13: Battle of Artois ends
French offensive at Artois fails, and the stalemate on the Western Front continues.
17: Russians emerge victorious at Sarikamish
The Battle of Sarikamish between Ottoman and Russian forces in the Caucasus campaign ends. The Russian Caucasus Army emerges victorious over the Turkish 3rd Army which suffers close to 60,000 casualties in severe Russian winter conditions.
26: Raid on the Suez Canal commences
German-led Ottoman Army force advanced from Southern Palestine to attack the British Empire-protected Suez Canal.
31: Battle of Bolimow
The Germans fire eighteen thousand gas shells of xylyl bromide; a type of tear gas, in a large scale chemical attack on the Russians. The attack is a failure as the gas freezes in cold weather and is ineffective. A large Russian counter attack involving 11 divisions is smashed by German artillery fire with the Russians suffering some 40,000 casualties.
4: The Ottomans fail to capture the strategic Suez Canal
4: Germany first unrestricted submarine warfare campaign begins
Germany decides to launch unrestricted submarine warfare in the Atlantic. German U boats cannot be detected and will be highly successful in the coming summer.
7 – 22: Second Battle of the Masurian Lakes
The battle is part of the four offensives planned by the Central powers in the winter of 1915. The German Eighth and Tenth Armies emerge victorious gaining a toehold in Russian territory. The Russian 20th Corps, Tenth and Twelfth Army however are able to stop further advance ending the battle.
19: Gallipoli Campaign begins
The French and British naval ships launch an attack on the Strait of Dardanelles, beginning their Gallipoli Campaign.
17: The Battle of Champagne ends
The French Fourth Army gains little useful ground against the German 3rd Army, until this long campaign is called off. The Battle of Champagne ends in a French defeat and they take over 90,000 casualties, twice as many as the Germans.
22: Siege of Przemyśl ends
The longest siege of the First World War (133 days) ends after Austro-Hungarian forces are no longer able to hold the town of Przemyśl against surrounding Russian forces.
22: Second Battle of Ypres begins
24: First act of Armenian Genocide
In the first major event of the Armenian Genocide, also known as Red Sunday, leaders of the Armenian community are deported to two holding centers near Ankara; following the orders of Ottoman Minister of the Interior, Talaat Pasha.
26: Treaty of London is signed
A secret pact is signed between the Triple Entente and the Kingdom of Italy. The Allies succeed to gain the alliance of Italy against its former allies, including the German Empire and Austria-Hungary.
1: Gorlice-Tarnów offensive begins
On the Eastern Front, Austrians are struggling to prevent the Russians from crossing the Carpathian Mountains. Putting aside their plans of a German offensive in France, one German and one Austro-Hungarian army under General Mackensen attack along a 30-mile front, breaking through the Russian lines in Galicia.
7: Lusitania Sinks
A German U-Boat (submarine) sinks British passenger ship Lusitania off the south coast of Ireland. The sinking kills over a 1000 civilians including women and children and Germany is accused of breaching international Cruiser Rules. The Germans justify their attack arguing that Lusitania was carrying hundreds of tons of war munitions. The event plays its role in shifting the public opinion against Germany in neutral countries, especially the United States; which loses 128 of its citizens onboard the ship.
23: Italy declares war on Austria-Hungary
Almost a month after the secret Treaty of London, Italy declares war on old Triple Alliance ally Austria-Hungary.
25: Second battle of Ypess ends
Fought for the control of the town of Ypres in western Belgium between the Allied and German forces, the battle ends in another stalemate on the Western Front. It is remembered for initiating the modern era of Chemical Warfare by Germany; as it launches poisonous gas chlorine on Allied trenches killing close to 5000 French and Algerian soldiers.
22: Gorlice-Tarnów offensive ends
The offensive ends with the Russians being pushed back on a front extending from the Carpathians to the Baltic Sea. The German and Austro-Hungarian armies have retaken the fortress cities of Przemyśl and Lemberg.
23: Italian Offensive begins at Isonzo River
The Italian Second and Third armies numbering 460,000 under Field Marshal Luigi Cadorna, launch an offensive against Austria-Hungary under Archduke Eugen along the Isonzo River. This marked the beginning of the ‘First Battle of Isonzo’. Over the next 2 years, the Italians would mount eleven more offensives lasting until the autumn of 1917 losing many men and with no conclusive victory.
6 – 21: August Offensive of the Gallipoli Campaign
Also known as the Battle of Sari Bair, the offensive represented the final attempt made by the British Empire to seize control of the Gallipoli peninsula from the Ottoman Empire during the First World War.
21: Italy declares war on the Ottoman Empire
1: Germany suspends unrestricted submarine warfare
The backlash from the Lusitania sinking among others of a similar nature forces Germany to scale back the unrestricted submarine warfare campaign. In this highly successful phase of the campaign, 16 U-boats were destroyed, while they themselves sank 370 ships. There is however considerable diplomatic damage and heightened risk of neutral nations entering the war against Germany.
8: Tsar takes command in Russia
Exasperated with the recent defeats of the Russian Army, Tsar Nicholas II removes Grand Duke Nicholas Nikolayevich as Commander-in-Chief of the Russian Army. Nicholas II decides to personally take command of the army, something which would further weaken his control over the nation, with every defeat being closely tied with him and shattering the image of a divine infallible tsar.
23: Bulgaria begins mobilization
The Central and Allied powers had been long persuading Bulgaria to join the war on their sides. Bulgaria’s recent conflicts with the Serbians, and Allied losses in Gallipoli and Gorlice campaigns, convince the Bulgarian King Ferdinand to join the Central powers. On 23rd September 1915, Bulgaria begin mobilizing for war.
6: Invasion of Serbia begins
On October 6, German and Austro-Hungarian forces crossed the Danube and Save rivers, invading Serbia under the leadership of General August von Mackensen. Belgrade falls three days later on the 9th, forcing the Serbian government to flee to the city of Nisch.
15 – 19: Allies declare war on Bulgaria
With Bulgarian forces invading Serbia along with Germany and Austria-Hungary, the British Empire declare war on Bulgaria on the 15th. France follows the next day, while Italy and Russia declare war on the 19th.
25: Serbia retreats
Serbian Field Marshall Radomir Putnikwere orders full retreat south and west through Montenegro and into Albania. This is a great victory for the Central Powers as the Serbian army collapses. It will retreat to the Adriatic Sea and will eventually be evacuated by the Italian and French Navies.
26: The battle of Lake Tanganyika begins
In Africa, the battle for the control of the strategic Lake Tanganyika begins between the British Royal Navy, Force Publique and the Imperial German Navy. The Battle for Lake Tanganyika is the only naval battle in WWI that will be fought on a lake, rather than on the open sea.