Captain Mitchell was one of Captain Rachel Parker's foremost officers. On July 11, 1951, Parker was leading the convoy that contained the British's 'secret weapon' (an Angel). They were ambushed by the Chimera in Manchester on their way to the exchange with the Americans in York, in which Parker and her squad were captured. Mitchell led a company tasked with rescuing the convoy (or at least its Angel), which was stranded on the west side of Manchester. For hours they fought their way through the infested city against the Chimera from absconding the Angel.
Mitchell had been pinned down near the convoy by Stalkers, making immediate air support of any kind impossible. Parker, having been rescued from Grimsby, ordered as many soldiers as possible to help recover the convoy's cargo and reinforce Mitchell. Mitchell had been fighting a losing battle for most of the morning, but finally made it to the convoy site - however, the Chimera got to it first. With the help of Sergeant Nathan Hale, they managed to take the site and hold off a counterattack from a squad of Hybrids augmented by a Stalker. After they secured the area, Mitchell radioed Parker and reported their success, and the container was later airlifted to Northern Command.
Mitchell later participated in Operation Shear to take out a Chimeran tunnel nexus in Nottingham, where the Chimera were excavating something out of the ground. Mitchell helped Lieutenant Stephen Cartwright take control of the dig site and afterward they were all sent back to Southern Command for a well earned rest. However, Southern Command came under attacked, as Mitchell, along with his squad and Lieutenant Cartwright were at the northern entrance of the base, protecting it from Chimeran forces in order to provide the VTOL transports in the hangar some time to escape. He and his squad were still fighting when Cartwright and Hale escaped Southern Command in a Stalker. Mitchell survived the attack with a visible leg wound and escaped on the last VTOL to a makeshift camp in Cardiff.
Although he is seen throughout the game, Mitchell's personality is not often revealed. At times he appears to be a little sarcastic and has a no-nonsense attitude when it comes to leading his men. He is well headed in battle and brings a calmness when in a dangerous situation. He is a skilled commander, especially when attacking enemies. When attacking a Chimeran area, he usually remarks "make the place bloody sterile". Mitchell cares for his men, and the first thing he does after every victory is seeing to the wellbeing of those under his command.
Mitchell wears a standard British army uniform and carries different pieces of equipment like grenades and bullets. He carries a large radio on his back and uses a Mk.6 Carbine . He has no distinct facial features, as he is made from a generic British soldier model and looks like most of the other soldiers.
- Aside from a cutscene at the end of the Manchester level, he does not properly appear in the game, as he looks just like a normal British soldier.
- Captain Mitchell's voice changes many times, e.g. in the first Manchester level, (the path of "Least Resistance") when he says "you better hurry, the Chimera want this as much as we do", he sounds almost like Stephen Cartwright, but in the third level ("Outgunned") he sounds much older, probably in his 40's. However, in the final cutscene of Manchester when he says "Mitchell to command, site secure, all stalkers down. We've got your convoy, how about getting us a sodding medic!" he sounds younger like he's in his early 30's.
- Mitchell makes no further appearances in Fall of Man after the events in Bristol.