With improved dreadnought battleships and the construction of the Coast Defenses of Long Island Sound at the beginning of the 20th century, these batteries became obsolete, and Ft. Slocum was removed in 1907 from the Artillery District of New York (Coast Defenses of Eastern New York from 1913), leaving Fort Totten and Fort Schuyler in that role until 1935. However, Fort Slocum retained all its guns until World War I. At the start of the 20th Century Davids Island became the East Coast assembly point for units assigned to America’s new overseas territories.