The Gallipoli campaign was an attack by England and France against the Ottoman Empire. Soldiers from Australia, New Zealand, India and Canada aided the forces from the United Kingdom, while France's force included troops from French West Africa. The Ottomans had support from Austria-Hungary and Germany.
One of the chief difficulties the Allies faced during World War I was the fact that Russia's main route to the sea passed through the Dardanelles, a strait controlled by the Ottoman Empire. As the Ottomans had come into the war on the side of Austria and Germany, this meant Russia's naval power and shipping capacity were both crippled. The Gallipoli campaign was an amphibious attack launched in April 1915 aimed at securing the Dardanelles and then attacking Constantinople.
The Gallipoli campaign was a major failure on the part of the Allies and an unexpected victory for the crumbling Ottoman Empire. After more than eight months of fighting and around 250,000 casualties on each side, the Allies withdrew. The war served as an important point of national pride and identity for Australia and New Zealand, and it led directly to the rise of Kemal Ataturk and the founding of the Republic of Turkey eight years later.