The U.S. Army’s first Future Combat System (FCS) equipped Brigade Combat Team (BCT) becomes fully operational in 2015. Concern for the possibility of combined arms capability gaps between planned FCS capacities and those required to defeat the expected 2015 dominant threat model – the Extremist Guerrilla Army – led to a study of combined arms operations. This thesis identifies 13 combined arms enabling capabilities necessary for FCS BCT success in the complex and lethal 2015 operational environment. These capabilities will defeat the Extremist Guerrilla Army, maintain freedom of movement across the battlefield, and positively influence the local populace to support U.S. objectives. Five FCS BCT capability shortfalls were identified. These are areas in which FCS BCTs will not be fully capable in the operational environment of 2015. These areas include the need for ruggedized SATCOM antennas, allowing units to stay connected to FCS voice and data information networks while on the move. FCS vehicles also need to be hardened against electronic attack in an age of nuclear proliferation. Engineer vehicle variants will need to be produced to support route future clearance and gap crossing missions. Finally, the enemy’s expected heavy use of Information Operations (IO) demands that the Army organize company size IO units to support FCS BCTs.