A Synopsis of the Secretaries of Defense - Bob Navarro - Bog

The Secretary of Defense has authority, direction and control over the Department of Defense, and is designated as the principal assistant to the President in all matters relating to the Department of Defense. The Secretary of Defense is in the chain of command for both operational and administrative purposes, subject only to the orders of the President, over all Department of Defense forces: the Army, Navy, Marine Corps and Air Force. This is also extended to the Coast Guard during any period of time in which its command and control is transferred to the Department of Defense.