combatants

belligerents

dogfaces, fighters, legionaries, legionnaires, men-at-arms, regulars, servicemen, soldiers, troopers, warriors

servicewomen

carabineers (or carabiniers), cavaliers, cavalrymen, cuirassiers, dragoons

doughboys, footmen, foot soldiers, grunts, infantrymen

commandos (or commandoes), raiders

jarheads [slang], marines, rangers

artillerymen, cannoneers, gunners, mortarmen, musketeers, riflemen

archers, crossbowmen

lancers, pikemen, spearmen

Confederates, Continentals, Federals, GIs (or GI's), guardsmen, militiamen, minutemen

counterguerrillas (also counterguerillas), guerrillas (or guerillas), irregulars, paramilitaries, partisans (also partizans)

lifers, veterans, warhorses

conscripts, draftees, enrollees, recruits

reservists

champions, knights

diggers [chiefly Australian & New Zealand], gallowglasses, gendarmes