Frolov is first seen during the first Russian campaign level. The player must get up to the mill where he and three other soldiers were already waiting for the player and the squad after the trench battle against the German infantry and armor. He is presumably in the 67th Guards Rifle Division due to his presence in the infantry unit as a platoon commissar. He briefs the player and the squad on how they must capture and hold the small village to stop the Germans from flanking their force. After he briefs the player, he may be killed by German infantry or tanks from the assault or capturing of the village. However, if he lives, he will reappear in Ponyri assault as leader of 5th platoon acting as reinforcement for Sgt. Antonov's squad.
In Botovo, Sgt. Frolov fought against German onslaught with a stolen Luger after losing his weapons. If he lives, in Ponyri, he still wields the same pistol if he's not using his SVT Tokarev.
He reappeared briefly on the Kharkov mission riding atop a T-34 tank and leading his own platoon. He commanded his platoon by waving his pistol forward, which is still the same pistol that he used in Botovo.