On November 12, 1918, one day after an armistice ended World War I, the Allied fleet passes through the Dardanelles, the narrow strait running between Europe and Asia that had in 1915 been the site of a disastrous Allied naval operation.
As the only waterway between the Black Sea in the east and the Mediterranean Sea in the west, the Dardanelles was a much-contested area from the beginning of the First World War. The naval attack, spearheaded by Winston Churchill, Britain's young first lord of the Admiralty, opened on March 18, 1915, when six English and four French battleships headed toward the strait. Turkish mines blasted five of the ships, sinking three of them and forcing the Allied navy to draw back until land troops could be coordinated to begin an invasion of the Gallipoli peninsula. With troops from the Ottoman Empire and Germany mounting a spirited defense of the peninsula, however, the Gallipoli offensive turned into a significant setback for the Allies, with 205,000 casualties among British Empire troops and nearly 50,000 among the French.
Allied troops had more success, though, with their later offensives in Mesopotamia and Palestine. By September 1917, the crucial cities of Jerusalem and Baghdad were both in British hands. As the war stretched into the following year, these defeats and an Arab revolt had combined to destroy the Ottoman economy and devastate its land, leaving some 6 million people dead and millions more starving. In early October 1918, unable to bank on a German victory any longer, the Turkish government in Constantinople sought to cut its losses and approached the Allies about brokering a peace deal. On October 30, British and Turkish representatives signed the Treaty of Mudros, ending Ottoman participation in World War I. By the terms of the treaty, Turkey had to demobilize its army, release all prisoners of war, and evacuate its Arab provinces--the majority of which were already under Allied control--and open the Dardanelles and Bosporus to Allied warships.
This last condition was fulfilled on November 12, the day after the general armistice, when a squadron of British warships steamed through the Dardanelles, past the ruins of the ancient city of Troy, toward Constantinople. By the post-war terms worked out by the Allies and formalized in the Treaty of Sevres in 1920, the waterways formerly under Ottoman rule--including the Dardanelles, the Sea of Marmora and the Bosporus--were placed under international control, with the designation that their "navigation...shall in future be open, both in peace and war, to every vessel of commerce or of war and to military and commercial aircraft, without distinction of flag."