Corporal John Nichols is the main playable character of the American Campaign and one of the protagonists in Call of Duty 3.
He proves himself to be an excellent marksman and hand-to-hand combatant.
Nichols first appears in Call of Duty 3 in a camp near Saint-Lô, with Pvt. Leroy Huxley, and other soldiers. There, Huxley teaches Nichols and Travers how to shoot and throw grenades. Nichols later has to bash a crate open to get a Thompson Submachine Gun. He and his squad then load into the truck. This is when Nichols is first introduced to his sergeant, Frank McCullin. They are introduced to his 'rules': "Rule 1. You're no good to me dead. Rule 2. Ah, what does it matter? You'll all probably end up dead anyway." The squad then sets off for Saint-Lô.
On the way to Saint-Lô, the truck his squad is in gets hit by German artillery fire. It rolls, Nichols is injured and becomes unconscious, and when Nichols regains consciousness, Cpl. Mike Dixon pulls him to the regroup position. There, Sgt. McCullin is gives orders to Pfc. Salvatore Guzzo. Nichols then gets his orders and get boosted over a wall into the fight routing the Germans out of Saint-Lò. After this, McCullin's 29th Division, Nichols included, joins with the 90th Infantry Division and immediately take part in a mission in the village of Saint Germain-Sur-Seves, where Nichols engages several German soldiers in hand-to-hand combat. During the next round of fighting in Mayenne, Huxley is wounded and McCullin is killed, so Dixon takes command of the squad. Dixon moves the squad to the Foret d'Ecouves to clear out a number of remaining German troops for the 2nd Battalion.
Dixon's men are then sent to defend the city of Chambois from an attempted German invasion. During the fighting Guzzo gets injured and Dixon hurries to rescue him. In his attempt, Dixon manages to save him, but at the cost of his own life. The squad fight on and encounter German mortars, which Nichols elimates. Nichols then uses two unmanned Pak 43s to destroy some German APCs. Eventually, the squad secures the town with the help of some air support.
After the battle concludes, Nichols is loaded onto a truck along with Guzzo, Huxley, and several new soldiers. Guzzo has earned a promotion and so, he is Nichols' new squad leader.