The American campaign begins with Private Martin, a member of the 506th Parachute Infantry Regiment, training at Camp Toccoa in the U.S. state of Georgia, on August 9, 1942. This level is meant to familiarize the player with the game controls. The player learns the basics of the game by completing an obstacle course and then having weapons training with Sgt. Moody.
The first mission occurs toward midnight on 5 June 1944, as part of the airborne operations which began the invasion of Normandy. The mission begins as Martin lands outside the town of Sainte-Mère-Église as a pathfinder to lay a drop zone beacon for other paratroopers. The paratrooper drops end up being scattered, leaving Martin in a mixed unit formed from various companies. This mixed unit clears nearby farmhouses of German soldiers.
In the next mission, the group then fights to capture Sainte-Mère-Église. They also disable several Flakpanzers (anti-aircraft tanks). A paratrooper is seen hanging from the town church.
The third mission begin when they manage to hold off the town until early morning, when the soldiers are suddenly attacked by German mortar fire, infantry, and a tank. Martin must acquire a Panzerfaust from the church to destroy it. Afterward, he and a few others must go reinforce the northern approach to the village where Martin must take out another tank. The soldiers then attack the German mortar crews. Captain Foley realizes he must get word to battalion headquarters that he needs reinforcements. He assigns Martin, along with Pvt. Elder and Sgt. Moody, to drive from Sainte-Mère-Église to Sainte-Marie-du-Mont in a "French tin can", as Moody refers to the car.
The fourth mission begin when Martin, Pvt. Elder and Sgt. Moody are along highway N13, meeting fierce opposition but they are able to keep driving until their car is damaged by a tank. They then go to a garage to commandeer a Kubelwagon. They hurriedly drive away and arrive safely at the battalion headquarters.
In the fifth mission, Martin and several others assault Brécourt Manor to destroy German artillery which has been hindering progress at Utah Beach. After this mission, it is revealed that Martin's unit will be detached from the 101st Airborne Division for special missions behind enemy lines, due to outstanding performance.
In the next mission, on 7 August, Martin and his unit assault a château in the Bavarian Alps of Germany to rescue two British officers (Captain Price and Major Ingram), and to find maps and documents. However, Major Ingram has been moved to another location.
The seventh mission, on 18 September, requires the unit to free Major Ingram from a prisoner camp, Dulag III-A, outside of Strasshof, Austria (not a country but a part of Germany during this time). This mission is timed, requiring the player to break the officer free and return to the escape truck within ten minutes before the Germans can arrive with reinforcements.
In the final mission, Private Martin's unit is northeast of Bastogne, Belgium on 15 January 1945. The unit clears out two bunkers and takes documents from them. After acquiring the documents, two Panzer tanks come over a ridge (mysteriously out of a minefield) and are accompanied by numerous soldiers. The player must use the Flak 88s and Panzerfausts in an effort to take out the tanks. After this is over, the American campaign ends with Foley congratulating Martin on his actions and ends stating, "I can hardly believe, it's over."
The first mission of the British campaign has Sergeant Evans and a unit from the 2nd Oxford and Bucks of the 6th Airborne Division take part in Operation Tonga. Just after midnight on 6 June 1944, the unit is dropped from Horsa gliders alongside the Caen Canal near Pegasus Bridge, Bénouville. They capture the bridge and defend it from the nearby German forces. (Captain Price (WW2) participates in this operation and several other missions as the commanding officer, although most of these missions occur before his capture.)
The next mission is just past noon of the same day, the unit protects the bridge from German counterattack, which includes several tanks. They hold the bridge until reinforcements from the 7th Parachute Battalion arrive.
The third mission, on 2 September, has Evans working alone, now with the Special Air Service or SAS. He is inserted next to the Eder Dam and destroys the anti-aircraft guns protecting it. During Operation Chastise the previous May, the No. 617 Squadron RAF destroyed the dam using bouncing bombs. However, the Germans had rebuilt it. The British Special Operations Executive wish to destroy it again to hinder German production in the Ruhr Valley. Evans also destroys the electrical generators in case the dam is not destroyed by the bombs. Evans escapes on a German truck stolen by Captain Price and Sergeant Waters.
In the fourth mission, the three men drive to an airfield while evading motorized patrols. Panzerfausts found on the truck can be used to destroy the enemy vehicles. When they arrive at the airfield, Evans needs to shoot down several Stuka dive bombers. The men escape in a stolen FW-200 Condor.
Then, in the next mission on 27 October, the three infiltrate the German battleship Tirpitz, near Tromsø, Norway. Evans and Captain Price board the ship in disguise using forged papers. Evans plants explosives, retrieves the ship's patrol logs and documents indicating the fleet movements of the Kriegsmarine (the German navy), and makes it back to the boat. However, Captain Price has been killed.
The final mission has Sergeant Evans' unit near Burgsteinfurt, Germany on 2 February 1945. The unit is sent to destroy some mobile V-2 rockets. When they finally reach it, it turns out they do not have enough explosives to destroy them completely. Consequently, Evans must fuel the rockets up, and use the fumes to increase the explosion effectively destroying them. They then fight their way to an extraction point on the other side of the bunkers surrounding the V-2 rockets.
The first Soviet mission occurs during the Battle of Stalingrad, on 18 September 1942. Private Alexei Ivanovich Voronin is on one of many barges transporting Soviet soldiers across the Volga River, many of which are destroyed on the way by German artillery or Luftwaffe aircraft. Once across, Voronin is unarmed and must avoid machine gun fire and find Borodin, an experienced sniper to help him. Soviet artillery eventually clears out the German machine guns, allowing Voronin and the others to enter Red Square.
The second mission begins in Red Square with many retreating Soviet soldiers being killed by fellow Soviets. Voronin helps capture the square, which is defended by two tanks and some machine guns. He does this by taking a flanking maneuver with a fellow Soviet soldier and finds a sniper rifle in a building overlooking the German front lines. After killing the German officers who have been calling reinforcements, Soviet artillery destroys the tanks. The unit makes their way through the rubble-filled streets to a railway station.
In the next mission, Voronin travels through the train station and part of the city to reach Major Zubov of the 13th Guards Rifle Division. Following this, Voronin is promoted to Junior Sergeant.
The fourth mission, on 9 November, has Voronin moving through the sewers to avoid snipers, making his way to an apartment building recently captured by the Germans.
The fifth mission has the unit under the command of Sergeant Pavlov to capture and defend an apartment building. First, Voronin acts as a counter-sniper while Kovalenko draws the fire of the snipers in the building; the unit then clears the building of Germans, and defends against the German counterattack.
The sixth mission occurs much later, on 17 January 1945, with Voronin promoted to full Sergeant, and now part of the 150th Rifle Division of the 3rd Shock Army. The unit secures a German train repair facility in Warsaw in the midst of the Vistula–Oder Offensive.
The next mission takes place just after securing the facility, with the unit making their way to the outskirts of the factories to regroup with the 4th Guards Tank Army.
Due to shortages in experienced soldiers, the eighth mission, on 26 January, requires Voronin to command a T-34-85 tank for the 2nd Guards Tank Army. Along with other tanks, he makes his way toward a town near the Oder River.
The ninth mission is also fought in the tank, with Voronin destroying some anti-aircraft weapons and securing the town.
In the final mission, on 30 April 1945, Sergeant Voronin is returned to the 150th Rifle Division. His unit battles in Berlin to reach the Reichstag, and they raise the Victory Banner atop the building.