CAN SOMEONE TELL ME THE TITLE OF A VAMPIRE MOVIE?

The movie came out in the 80s, it's about a medic who has been to several wars, and discovers a platoon of vampires who fight american wars and feed off of the dead, the medic is wounded, and the vampires offer to bite him, so he can continue his practice forever. Can't remember the title for the 'life' of me, hehe. Any help would be appreciated.