We used to have an annual Navy vs. Marines paintball battle. About 50 people per side.
The Marines would always work on tactics and battle plans. The Navy (usually half drunk, sometimes with beer on the battlefield) would run out and start shooting.
In my 6 years of participation, the Navy was 6-0. Pissed them off beyond belief.
With that said, if it was real bullets, I certainly wouldn't want to be on the other side of the Marines.