Amphibious landing, the largest in history until World War II. The Gallipoli campaign was an Allied operation in 1915 on the Gallipoli Peninsula of European Turkey in the battle between the Allies and Turkish forces for the control of the Dardanelles Straits.
The Gallipoli campaign proved an expensive enterprise. A half million men had deployed to the Dardanelles, of whom about 252,000 became casualties. Turkish records are incomplete, but their official casualty record of 151,309 is undoubtedly far too low. Regardless, the way to Constantinople was still blocked and would remain so for the rest of the war. Russia was cut off from easy access to its Allies, and the ensuring economic chaos helped bring on the Russian Revolution of 1917. Instead of morale-building victory, the Gallipoli campaign had brought the British and French a costly failure.
taken from - Spencer C. Tucker et al., eds., World War I Encyclopedia: Volume II: E-L (Santa Barbara: ABC-CLIO, 2005): 461-464.