"Soap" begins his SAS career hours before the six-day global war begins. He starts out as a Sergeant, unusual in that newcomers to the SAS are usually demoted to Trooper so that they must learn from the ground up (Soap is likely a replacement for a recently deceased Sergeant and has transferred from another unit). He is given a quick training session in weapons and techniques by Gaz, before being introduced toCaptain Price and the rest of Bravo Team. After passing the CQB (Close Quarters Battle) test (intended to be reminiscent of the real SAS "Killing Houses"), Soap is briefed on the mission to infiltrate and assault a cargo ship in the Bering Strait. On board the ship, they discover a nuclear bomb bound for Russia, though enemy MiGs interrupt their investigations, and Soap barely escapes with his life, being forced to leap for the ramp of their helicopter just as it begins flying away which causes him to lose his grip just to be rescued at the last second by Captain Price.
Upon completing the mission, Soap, Captain Price and Gaz move into Russia to extract the informant who supplied them with the intelligence for the cargo ship, a man codenamed Nikolai. Working in close conjunction with Russian government Loyalists led by Sergeant Kamarov, they successfully locate and extract Nikolai from the battle zone, though their helicopter is shot down byUltranationalist anti-aircraft missile fire. Bravo Team, Nikolai and another SAS operator are forced to fight their way through enemy lines, before being provided with support from an AC-130 Spectre Gunship, callsigned "Wildfire". They are extracted by helicopter under cover of heavy air support from Wildfire.
Soap's next mission with Bravo Team would take him to Azerbaijan. Clearing through an abandoned village, Soap witnessed Khaled Al-Asad's interrogation and execution by Captain Price. The next day, it appears Soap was designated the team's support man, being equipped with both an M249 and M21 sniper rifle. He was placed in charge of covering the team's retreat with the Minigun from a downed Black Hawk (destroying several Ultranationalist Helicopters in the process) and detonating the explosive charges placed at Phase Line Bravo. Afterwards, he was the point man when the squad had to backtrack to the lower part of the village due to heavy coverage of Anti Aircraft weapons in the vicinity.
MacTavish's final mission in the Russian civil war saw him infiltrating Russia as part of the joint task force of US Marines and SAS operators in order to eliminate Imran Zakhaev's nuclear capability. He was in charge of destroying the electricity supply to the facility, and then, during the escape, provided all-around covering fire for their jeep as they made their way to the extraction site. Fighting fiercely at the bridge during the penultimate battle, he was thrown to the floor and severely injured by an exploding tanker. He was pulled into cover by SSgt. Griggs, moments before Griggs was killed, and watches helplessly as Imran Zakhaev and his bodyguards execute Gaz and two SAS operatives. Just as all hope seems lost, a Loyalist Mi-28 gunship destroys the Ultranationalist Mi-24 Hind, forcing Zakhaev and his henchmen to turn away from Soap and open fire on the helicopter. A heavily wounded John Price slides Soap his M1911 pistol, which enables him to personally kill Imran Zakhaev and two of his bodyguards. Moments later, Loyalist forces flood the scene and Kamarov comes to Soap's aid by helping him onto a stretcher, assuring him that he will be alright. Soap passes out during the middle of extraction and is revealed to have survived as the events of Modern Warfare 2 begin.
After the events of the civil war, MacTavish is promoted to Captain and is a squad leader of Task Force 141 alongside Lieutenant Simon "Ghost" Riley and Sergeant Gary "Roach" Sanderson. MacTavish and Sanderson infiltrated Kazakhstan to recover an ACS module and escape on snowmobiles. Shortly after the mission, MacTavish leads Task Force 141 to capture Rojas in Rio De Janeiro only to find out from Rojas that Makarov has a strong hatred for Prisoner 627 in a Russian gulag. The task force is then swarmed by the Brazilian Militia but is saved by Nikolai, who had fought alongside Soap during the events of Modern Warfare.
Shortly after extracting from South America, MacTavish and Task Force 141 initiates a two-stage operation, the first stage being to secure a modified oil platform in order to disable SAM sites on the platform, and the second phase to infiltrate the prison itself. After infiltrating the prison, MacTavish leads forces through a Russian gulag, and reunites with Captain Price (known as Prisoner 627). Although Price is at first hostile towardsRoach he rejoins after recognizing Soap and the squad manages to extract (via SPIE rig) from the area. During this time, MacTavish returns John Price's M1911 pistol he used to kill Imran Zakhaev five years earlier.
During the events of "Contingency", MacTavish facilitates Price's infiltration inside a submarine by providing Predator drone support. After the events of the nuclear launch, Task Force 141 was split up to go investigate two locations, with Price and MacTavish investigating an arms deal in Afghanistan, while Ghost and Sanderson and the bulk of the task force investigate one ofMakarov's safehouses in Russia. Price and MacTavish are attacked by Shepherd's men and attempt to warn Ghost and Sanderson, only to be late in the process. Soap and Price manage to escape the arms deal with the help of Nikolai while getting some intelligence from Makarov, focusing on killing Shepherd.
The duo then pursues Shepherd through Afghanistan, where they eventually corner him and attempt to kill him. However as MacTavish attempts to stab Shepherd, the latter disarms Soap, knocks him to the ground and impales him with a knife. Before Shepherd can execute MacTavish, Price tackles Shepherd and engages him in a long hand-to-hand fight, withShepherd eventually gaining the upper hand. However Soap, now awake takes out the knife in his chest and throws it at Shepherd, killing the general for good. Price then comes to Soap's aid and the two are evacuated by Nikolai, who arrives in a MH-6 Little Bird. During the course of Shepherd's betrayal, Soap and Price are labeled as international fugitives, and are on the run at the end of the game.