What was the biggest amphibious operations of World War I?

The first large scale amphibious operations, ones that were to heavily influence theorists in the decades to come, were conducted as part of the Battle of Gallipoli in 1915 against the Ottoman Empire during World War I. the purpose of the battle was to capture the capital of the Ottoman Empire (modern-day Istanbul). Although the naval attack was repelled and the land campaign failed, the campaign was the first modern amphibious landing, and featured air support, specialized landing craft and a naval bombardment.