United States Department of Defense United States Department of Defense The Department of Defense (DoD, USDOD, or DOD) is an executive branch department of the federal government charged with coordinating and supervising all agencies and functions of the government concerned directly with national security and the United States Armed Forces. The department is the largest employer in the world, with nearly 1.3 million active duty servicemen and women as of 2016. Adding to its employees are over 826,000 National Guardsmen and Reservists from the four services, and over 742,000 civilians bringing the total to over 2.8 million employees. Headquartered at the Pentagon in Arlington, Virginia,
Department of the East the 1916 Defense Act. It was replaced by the Second Corps Area. The headquarters of the 1853–1861 Department of the East in 1861 was Troy, New York, except for the few years under the command of Gen. Bankhead, when he made his headquarters at Ft. McHenry, in Baltimore, MD. The headquarters of the last Department of the East was originally located in leased office space in New York City until 1878, when the War Department relocated all headquarters functions across the country to army posts due to economic considerations. The headquarters was relocated to Fort Columbus, renamed Fort Jay in