sentences:  The sinking of the Maine resulted in the United States declaring war on Spain, and the entire U.S. Atlantic Fleet moved to Key West for the duration of the war.During World War I (1914–1918) the base was expanded again, and in 1917, a U.S. naval submarine base was established on the main island of Key West on what is now naval air station "annex" property.Its mission during World War I was to supply oil to the U.S. fleet and to block German ships from reaching Mexican oil supplies.