The Department of Defense (Defense Department, CSDOD, DOD, DoD or the Fortress) is the Executive Department of the Government of the Union of Christian States charged with coordinating and supervising all agencies and functions of the government concerned directly with national security and the Christian States Armed Forces. The Department is also the largest employer in the world, with more than 1.13 million active duty soldiers, sailors, marines, airmen, and civilian workers, and over 1.1 million National Guardsmen and members of the Army, Navy, Air Force, and Marine Reserves. The grand total is just over 2.2 million servicemen, servicewomen, and civilians.

The Department – headed by the Secretary of Defense – has five subordinate military departments: the Christian States Department of the Army, the Christian States Department of the Navy, the Christian States Marine Corps, the Christian States Department of the Air Force, and the Christian States Coast Guard. In addition, there are many Defense Agencies such as the Defense Intelligence Agency (DIA), the National Geospatial-Intelligence Agency (NGA), the National Reconnaissance Office (NRO), the Defense Advanced Research Projects Agency (DARPA), the Defense Logistics Agency (DLA), the Missile Defense Agency, and the Fortress Force Protection Agency (FFPA), all of which are under the command of the Secretary of Defense.

The Department is allocated the highest level of budgetary resources among all Federal agencies, and this amounts to more than one-half of the annual Federal discretionary budget.