The Gallipoli Peninsula is located in Turkey. The peninsula overlooks a stretch of water called the Dardanelles, which connects the Mediterranean Sea with the Sea of Marmara. The Sea of Maramara is almost completely surrounded by Turkey and the country's capital, Istanbul (Constantinople during World War One) sits on the far side of it.
By the end of 1914 the Western Front had ground to a halt. The Allies thought an attack at the Dardanelles could be a new way of attacking the Central Powers.
Fighting at Gallipoli involved British, Australian, New Zealand, Indian and French soldiers, who fought against Turkish soldiers assisted by German officers.
The Gallipoli Campaign started in March 1915 and ended in early 1916 when the Allied forces were evacuated from the Gallipoli Peninsula.
The Gallipoli Campaign was a big disaster for Britain. Winston Churchill was kicked out of the government because of his support for the plan. The campaign had cost thousands of lives but the Allies were no closer to getting the breakthrough they needed against the Central Powers.