Walker is one of the few Lieutenants seen in Call of Duty 3 with the American forces. He first appears in the level "The Crossroads" when Walker is in melee attack with a German in a blown up room. Lt. Walker can die at any time but sometimes plays a roll in a cut scene. Lt. Walker is also seen making gestures to his men so they will storm a house on the level "The Island". Unfortunately, Lt. Walker is cut down by a German MP-40 along with two other soldiers.
Even though he can die at random times, Lt. Walker is always seen storming the house.