In the American campaign, the player controls Nichols, a replacement for the . After arriving in a staging area outside , he is assigned to his new squad consisting of veterans Mike Dixon, Private Leroy Huxley (voiced by ), and the squad's CO, Frank McCullin. Shortly after Nichols' arrival, the squad participates in the final offensive in the . Upon arriving at the outskirts of the town, McCullin enlists radio operator Salvatore Guzzo, who had become separated from his unit, to assist the squad in the attack, despite the latter's objections. During the brutal street to street fighting, the squad takes shelter from a German artillery barrage, during which Guzzo demands that the squad should fall back. As the shelling intensifies, Guzzo loses patience and tries to leave but is stopped by McCullin, who threatens to shoot him for desertion. After the squad fights off a final counterattack by the Germans, Saint-Lô is finally declared secure. Shortly after the battle, the squad is folded in with the as reinforcements to help secure . As the squad pushes forward and eventually succeeds in clearing the area, it becomes clear that McCullin, after witnessing years of war and death, is beginning to lose touch with reality, often appearing confused and distracted, even in the middle of battle.
- Call of Duty 3 is a historical first-person shooter game that has a single-player campaign mode and multiplayer mode It is open-ended, giving the player multiple paths to complete objectives, but plays similarly to the series' .
- Players fight alongside -controlled teammates against enemies who use various attack patterns, hide behind cover, and regroup to improved defensive positions.
- A character can be positioned in one of three stances: standing, crouching, or prone, each affecting the player's rate of movement and accuracy
- Using cover helps the player avoid enemy fire or recover health after taking significant damage
