I don't know where in the hell you get this information from. The Marine Corps used to be a department of the Navy but not anymore. Copied and pasted from Webpage..."""While the US Marine Corps is a separate and distinct service branch, it has many close ties to the US Navy, and the Department of the Navy""" I know every time I went to combat I wasn't supporting any other branch. In Afghanistan I was part of a JTF Operations Command with the Army but that was only because our unit at the time was SOTG and went in to Take back the area the Army had lost and couldn't control in Khoust Providence At FOB Salerno where Pat Tillman was killed by friendly fire.