Radar picket ships first came into being in the US Navy during World War II to aid in the Allied advance to Japan. The number of radar pickets was increased significantly after the first major employment of kamikaze aircraft by the Japanese in the Battle of Leyte Gulf in October 1944. "Fletcher"- and "Sumner"-class destroyers were pressed into service with few modifications at first. Later, additional radars and fighter direction equipment were fitted, along with more light anti-aircraft (AA) guns for self-defense, usually sacrificing torpedo tubes to make room for the new equipment, particularly the large height-finding radars of the era. Deploying some distance from the force to be protected along likely directions of attack, radar pickets were the nearest ships to the Japanese airfields. Thus, they were usually the first vessels seen by incoming waves of kamikazes, and were often heavily attacked.