Corps are the Army's largest tactical units, the instruments with which higher echelons of command conduct maneuver at the operational level. Corps are tailored for the theater and mission for which they are deployed. Once tailored, however, they contain all the combat, combat support, and combat service support capabilities required to sustain operations for a considerable period. Corps are commanded by Lieutenant Generals. Corps plan and conduct major operations and battles. They synchronize tactical activities including the maneuver of their divisions, the fires of their artillery units and supporting aerial forces, and the actions of their combat support and combat service support units. While corps normally fight a part of a larger force, they may also be employed alone, either as an independent ground force or as the Army or land component of a joint task force. When employed alone, they may exercise operational as well as tactical responsibilities. Corps may be assigned divisions of any type required by the theater and the mission. They possess organic support commands (Corps Support Command - COSCOM), and are assigned combat and combat support organizations based on their needs for a specific operation. Armored cavalry regiments, field artillery brigades, engineer brigades, air defense artillery brigades, and aviation brigades are the non-divisional units commonly available to the corps to weight its main effort and to perform special combat functions. Separate infantry or armor brigades may also be assigned to corps. Signal brigades, military intelligence groups, and military police groups are the usual combat support organizations present in a corps. Other units such as psychological operations battalions, Army special operations forces, and civil affairs units may be assigned to corps when required. Corps provides centralized control and coordination of the operations of the divisions, a function essential to effective combat. They also include reinforcing combat, combat support, and combat service support units which are employed directly or attached to lower units so as to influence the course of the conflict. By shifting the allocation of available resources, including reinforcing artillery, combat support, or combat service support, the corps commander can exploit a successful action, reinforce a unit under heavy attack or otherwise influence the outcome of the action. Highly developed unit combat intelligence collection and processing capabilities including ground and aerial surveillance, with specialized sensor devices manned and operationally controlled by qualified intelligence specialists and staffs, are essential at all levels of command. Specialized intelligence units and individual personnel such as prisoner of war interrogators, foreign document specialists, technical intelligence teams, field operation specialists, counterintelligence teams, and specialists in signal intelligence are available to reinforce organic capabilities. As the logistics support command assigned to the corps, the Corps Support Command [COSCOM] executes the corps CSS cell's support plan. The COSCOM provides logistics support to the corps force and to other units, Services, or allies as directed, to include a corps slice to offset LID shortages. The COSCOM coordinates logistics elements in support of corps forces or the current operational plans of unified or joint commands. It organizes different types of logistics units into a support package to meet the mission requirements of the supported force. While the COSCOM supports corps elements logistically, it depends upon corps elements for specific support. The corps issues mission-type orders to describe the support which the corps organizations provide in support of the COSCOM.
The First Digitized Corps Systems Architecture was delivered in late 1998. This architecture will become the III Corps when fielded. The First Digitized Division (FDD) was equipped in 2000, the Objective Digital Division in 2003, and the First Digitized Corps (FDC) by the end of 2004. The goal is all four corps and supporting AC/RC structure will be digitally equipped by the end of FY11.