He's the new replacement who's riding in the truck to Bastogne with all the Second Platoon guys -- Guarnere, Babe, Liebgott, Muck, Toye. They ask him if he's got any extra socks/grenades/smokes/&c. He introduces himself as Junior.

And yes! I believe he's the first person you see on We Stand Alone Together, which is just... unbelievably moving and wonderful.