Chronologically, this is the second title in the MnB series. In it, you control a squad of marines assaulting a Vietcong base, then holding out against an endless assault. Released in July 2nd 2004, it was succeeded by... Mud and Blood 2!
You can still play it on Newgrounds.
This game was a lot more random than our Mnb 2; weapons and support were completely randomized. Unlike MnB 2, you don't have Tactical Points, but you can't get reinforcements, and whenever you use radio commands, your merit will decrease and your requests will eventually get denied.