A battleship is a large armored warship with a main battery consisting of large caliber guns. During the late 19th and early 20th centuries the battleship was the most powerful type of warship, and a fleet centered around the battleship was part of the command of the sea doctrine for several decades. By the time of World War II, however, the battleship was made obsolete as other ships, primarily the smaller and faster destroyers, the secretive submarines, and the more versatile aircraft carriers came to be far more useful in naval warfare. While a few battleships were repurposed as fire support ships and as platforms for guided missiles, few countries maintained battleships after World War II, with the last battleships being decommissioned at the end of the Cold War.