Echelon above corps Echelons above corps ( EAC ) , in US and NATO practice , refer to higher headquarters , of purpose - built organization , which involve a greater number of troops than would be in an army corps . They may be standing organizations with a regional responsibility , or may be established for a particular operational purpose . While EAC most commonly refer to ground combat forces , they may refer to joint commands . They may also be administrative headquarters with responsibility for preparing combat forces . While there were a significant number of EAC in World War II , with increasing power of smaller organizations , it may not be required to have a ground force of the size of : Even in World War II , while the Western Allies used these terms , they were not universal . A Soviet army was roughly equivalent to a US or Commonwealth corps , with a front roughly equivalent to an army group . Japanese armies were also equivalent to US or Commonwealth corps , an area army to a western field army , and a general army to a theater . Current US concepts of EAC . The US Army divides types of troops into combat arms ( infantry , armor , artillery , aviation , special forces ) , combat support ( intelligence , communications , engineer , military police ) and combat service support ( supply , maintenance , medical , transportation , chaplain , finance and administration ) . Combat support . Military police , in the current environment , often are in a combat role . Doctrine is catching up with reality , as in Panama , and most recently in Iraq , with the Raven 42 patrol led by Staff Sergeant Timothy Nein and Sergeant Leigh Ann Hester , where a woman , for the first time , received the Silver Star medal , and qualified for the Combat Action Badge . Raven 42 , a unit of the 617th Military Police Company of the Kentucky National Guard , was on a convoy escort mission where combat was reasonable to expect , as opposed to the rear area MP units guarding prisons and POWs . Combat service support . Thomas J . Newman , a Quartermaster Corps major in 1993 , analyzes the roles of combat service support at EAC . It must be remembered that US Army doctrine was in flux as his monograph was being developed , analyzing the lessons learned from Operation Desert Storm , but the Army not yet gone to the major restructuring into units of action / brigade combat teams and units of employment . [ from the abstract ] Army concepts for supporting operations involving multiple corps were called into question by actions taken during Operations Desert Shield and Desert Storm . Non - doctrinal organizations provided support to U . S . forces deployed on these operations , despite the fact that doctrinally correct organizations existed . The monograph examines existing doctrine for support of multi - corps operations , and also doctrine for Army theater command and control architecture . It then summarizes support operations during the Gulf War Emerging logistics doctrine is then compared with both previous doctrine and with lessons learned in the Gulf . The monograph concludes that existing doctrine for support at echelons above corps requires revision , that - emerging doctrine is on the right track , and that a key requirement will be for the Army to identify a way to test new doctrine in a realistic manner . Existence of EAC ' s between US corps and unified commands . Still in use in US forces are Unified Combatant Command s , roughly equivalent to a theater . Multinational Force Iraq ( MNF - I ) is a level of command comparable to a reinforced field army .