The ultra rare Marine Corps dress uniform accessory you may never see USMC Marine Corps Dress Blues Uniform Grouping (WW2 through Vietnam) Dress Blues Explained The Dress Blue uniform, worn by Marines, is steeped in history, with roots dating back to 1798 when the secretary of war authorized the wearing of a blue uniform For all the people who don't seem to understand Marine Corps uniforms, the coat we wear is BLACK. When we wear our Dress Blues, it is a BLACK coat with BLUE pants ( Did you know? The Marine Corps' Dress Blues is the only uniform in the U.S. military designated to include the red, white, and blue colors of the American flag. This distinctive uniform R.S.A. Marine Corps Dress Blue Ceremonial Uniforms by TheRanger1302 on DeviantArt