The C.S. Marine Corps was modeled along the lines of the U.S. Marine Corps, and served essentially the same function as its northern counterpart. Confederate Marines served as guards at naval installations (major Confederate naval facilities had a marine barracks) and served in marine detachments aboard flag vessels and what are termed capital ships (major naval vessels). Someone can correct me on this, but I have been unable to find any significant marine involvement in the "brown water navy" -- the western rivers. However, a list of prisoners of war from a gunboat action in Louisiana I read about recently mentions a few marines captured on the "Queen of the West". From what I can tell, soldiers were usually detailed to man guns and perform other marine functions on the river gunboats. For example, Dunnington's naval force which defended Fort Hindman (Arkansas Post) in the attack of January 11, 1863, consisted in large part of men detailed from the 19th Arkansas Regiment and 28th Louisiana Regiment.