The Department of Defense, formerly known as the War Department, is one of the oldest and largest government agencies in North America. Established in 1789, it has a staff of more than 1.3 million people on active duty and over 68,000 civilian personnel. The department also employs nearly 1 million in the National Guard and Reserve forces. The Department of Defense, also known as DoD, provides the military forces needed to deter war and to protect the security of the United States. The department directs various branches of the U.S. armed forces, including the Army, Navy, Marine Corps, Air Force and Coast Guard. It offers war fighting, humanitarian aid, peacekeeping, disaster relief and homeland security services.