Campaign story

*NOTE: The story of Vanguard is told throughout various points in time in a non-chronological order.*

In August 1941, 2nd Lieutenant Lucas Riggs is stationed at Tobruk, Libya as part of the Australian-led Rats of Tobruk garrison. After a failed ambush attempt against a German convoy, Riggs is assigned to recover supplies for the British Army, alongside fellow Rat Private Desmond "Des" Wilmot and British Lieutenant Richard Jacobs. Riggs, Des and Jacobs manage to find intelligence relating to General Erwin Rommel, and destroy a German depot in the process, but they were detained by Major Henry Hamms for insubordination. In 1942, during the Second Battle of El Alamein, Riggs and the Rats are ordered by Hamms to form a defensive line, but Riggs disobeys the command and tries to retake a hill and call in bomber support with Des supporting him. The two of them succeed, though Des is killed in action. Angered by the disregard for the Rats' contribution to the fight, Riggs punches Hamms out of frustration, resulting in him facing prison time.

In June 1942, United States Navy pilot Lieutenant Wade Jackson participates in the Battle of Midway with his tail gunner, Aviation Machinist's Mate Mateo Hernandez. In November 1943, while assaulting the Imperial Japanese Army in Bougainville, Jackson and Hernandez's plane is shot down, and the two are captured by IJA soldiers. They are rescued by the 93rd Infantry Division, who later help them acquire an Imperial Japanese Navy Aichi D3A to assist the division in reclaiming the island.

In August 1942, Red Army nurse Polina Petrova witnesses the Germans invade Stalingrad. She fails to save her father Boris from being executed by enemy troops, but is able to escape with her brother Misha and several Soviet partisans. Petrova eventually acquires the nickname "Lady Nightingale" as she pursues Leo Steiner, the Wehrmacht commander responsible for the invasion. In January 1943, Petrova and Misha attempt to assassinate Steiner in Stalingrad, but Misha is severely wounded. He sacrifices himself to buy Petrova time to escape. Petrova eventually confronts Steiner and kills him and his personal army, inspiring the citizens of Stalingrad to reclaim the city from the Nazis. She then sets her sight on Steiner's superior, Hermann Freisinger.

In June 1944, British paratrooper Sergeant Arthur Kingsley takes part in Operation Tonga, where he and the Parachute Regiment help destroy the Merville Gun Battery and several other bridges to assist the Allied forces in invading Normandy. Kingsley befriends fellow paratrooper Sergeant Richard Webb, who would later become Kingsley's right-hand man.

Kingsley, Webb, Petrova, Jackson and Riggs, alongside a sixth soldier named Milos Novak, would eventually be recruited by Captain Carver Butcher to form the first special operations task force, callsign Vanguard. Kingsley is appointed as the leader of the task force. In April 1945, Task Force Vanguard hijacks a train to Hamburg, Germany, in search of intelligence regarding Project Phoenix, a secret Nazi program run by Freisinger. While infiltrating a Kriegsmarine submarine, the squad is captured by Freisinger's men, minus Jackson who evaded them, and Novak who is bludgeoned to death by Freisinger. Vanguard is delivered to the Gestapo headquarters in Berlin, where Freisinger appoints Schutzstaffel officer Jannick Richter to interrogate them. Jackson is also captured after attempting to steal a plane; Richter demoralizes the squad by executing Webb.

Being unaware of Project Phoenix's purpose and Freisinger's involvement, Richter attempts to learn more by interrogating Petrova and Riggs about Steiner and Rommel's connection to Freisinger. He deduces that the project was a coup attempt, in order to appoint Freisinger as the new Führer of the Fourth Reich. As Berlin falls under siege by the Red Army following Adolf Hitler's suicide, Riggs breaks out of interrogation and frees the squad, while Kingsley kills Richter to avenge Webb. Vanguard pursues Freisinger to the airport, where they finally apprehend him and burn him alive. The four then board Freisinger's Luftwaffe plane, discovering numerous German documents and assets, revealing global Nazi covert operations. Kingsley decides to follow up on Project Aggregat, a secret V2 rocket facility, and orders Jackson to fly there in pursuit.