I know some naval actions are embedded in popular history, but did the USMC play any part in civil way battles? Additionally, was there a ‘CSMC’ and what part did may they have played?
This older answer might be of interest for you.
Well there were some US Marines at the battle of bull run where the valiantly defended union cannon before being overrun, for them most part their served on union naval ships and also participated in naval landing such as the capture of the New Orleans and bombardment of fort Pulaski, but for the most part strategically speaking the marines did not play a pivotal role like the union army did, the CSA did have a marine corps commanded by Commandant Lloyd J Beall, and had around 900 to 1000 marines, CSMC marines saw service at the battle of Hampton roads but didn’t take part in any major naval landing because the CSA did not have the resources to do that, towards the end of the war the CSMC was ordered to serve as regular land infantry, where they served with distinction at sailors creek and helped defend Richmond from encroaching union forces, ultimately neither Corps played a pivotal role in the war as their respective armies did