Who is Spaag, Machine-gunner Spaag from The Killing Zone: My Life in the Vietnam War and what is their importance?

Spaag is one of the machine-gunners of Lt. Downs' platoon. He is described as a dependable man, originally from a farmer background in Minnesota. He is involved in the battle in the jungle where Lt. Downs is slightly wounded in the shoulder by grenade shrapnel. Spaag, like Lt. Downs also ends up with a serious wound.