2nd battle of ypres
During World War I, the Second Battle of Ypres was fought from 22 April – 25 May 1915 for control of the strategic Flemish Town of Ypres in western Belgium after the First Battle of Ypres the previous autumn. It was the first mass use by Germany of poison gas on the Western Front. For the first time, a former colonial force (the 1st Canadian Division) defeated a European power (the German Empire) on European soil (in the battles of St. Julien and Kitchener's' Wood, engagements during the battle).
22 April – 25 May 1915
gorlice-tarnow offensive
Initially conceived as a minor German offensive to relieve Russian pressure on the Austro-Hungarians to their south on the Eastern Front, but resulted in the Central Powers' chief offensive effort of 1915, causing the total collapse of the Russian lines and their retreat far into Russia. The continued series of actions lasted the majority of the campaigning season for 1915, starting in early May and only ending due to bad weather in October.
2 May – 22 June
battle of loos
The Battle of Loos was a World War I battle that took place from 25 September – 13 October 1915 in France on the Western Front, during the First World War. It was the biggest British attack of 1915, the first time that the British used poison gas and the first mass engagement of New Army units. The French and British tried to break through the German defences in Artois and Champagne and restore a war of movement. Despite improved methods, more ammunition and better equipment, the Franco-British attacks were contained by the German armies, except for local losses of ground. British casualties at Loos were about twice as high as German losses.
2 May – 22 June
landings at gallipoli
was a campaign of the First World War that took place on the Gallipoli peninsula (Gelibolu in modern Turkey) in the Ottoman Empire between 25 April 1915 and 9 January 1916. The peninsula forms the northern bank of the Dardanelles, a strait that provided a sea route to the Russian Empire, one of the Allied powers during the war. Intending to secure it, Russia's allies Britain and France launched a naval attack followed by an amphibious landing on the peninsula, with the aim of capturing the Ottoman capital of Constantinople (modern Istanbul). The naval attack was repelled and after eight months' fighting, with many casualties on both sides, the land campaign was abandoned and the invasion force was withdrawn to Egypt.
The campaign was the only major Ottoman victory of the war. In Turkey, it is regarded as a defining moment in the nation's history, a final surge in the defence of the motherland as the Ottoman Empire crumbled. The struggle formed the basis for the Turkish War of Independence and the declaration of the Republic of Turkey eight years later, with Mustafa Kemal (Kemal Atatürk) as President, who rose to prominence as a commander at Gallipoli. The campaign is often considered to be the beginning of Australian and New Zealand national consciousness
25 April 1915 – 9 January 1916
siege of kut el amara
Known as the First Battle of Kut, was the besieging of an 8,000 strong British-Indian garrison in the town of Kut, 160 kilometres (100 mi) south of Baghdad, by the Ottoman Army. In 1915 its population was around 6,500. Following the surrender of the garrison on 29 April 1916, the survivors of the siege were marched to imprisonment at Aleppo, during which many died. Historian Christopher Catherwood has called the siege "the worst defeat of the Allies in World War I".