The Dardanelles is a narrow waterway linking the Aegean Sea with the Sea of Marmara; the Gallipoli peninsula, part of European Turkey, forms the west bank and Asiatic Turkey the east bank. In 1915 British and Commonwealth troops invaded Gallipoli in an ill-fated attempt (the Dardanelles Campaign) to knock the Ottoman Empire out of the First World War. After heavy fighting, the expeditionary force evacuated the peninsula in 1916.