As early as 1900 the General Board of the United States Navy considered building advance bases for naval operations in the Pacific and the Caribbean. The Marine Corps was given this mission in 1920, but the challenge was to avoid another disaster like Gallipoli. The conceptual breakthrough came in 1921 when Major "Pete" Ellis wrote "Advanced Base Operations in Micronesia" a secret 30,000-word manifesto that proved inspirational to Marine strategists and highly prophetic. To win a war in the Pacific, the Navy would have to fight its way through thousands of miles of ocean controlled by the Japanese—including the Marshall, Caroline, Marianas and Ryukyu island chains. If the Navy could land Marines to seize selected islands, they could become forward bases.