How many marines do you know?
There is no possibility of a civil war with only two factions. There is also no possibility of a war where the military remains unified.
Look at the civil wars in Liberia for a more accurate snapshot of how an American civil war today is likely to go.
Sadly, it very easily go like that recent civil war in the Marshals. After that one was over no building larger than a porta potty remained unburned.
Complete with meth head 19 year old Warlords in Kiss Army t shirts and nicks like Brigadier General Skywalker?
Lord I hope not
Sherman on meth