5-79. A relief in place is an operation in which, by the direction of higher authority, all or part of a unit is replaced in an area by the incoming unit and the responsibilities of the replaced elements for the mission and the assigned zone of operations are transferred to the incoming unit (JP 3-07.3). (See figure 5-1. Note. The Army uses AO instead of a zone of operations.) The incoming unit continues the operation as ordered. A commander conducts a relief in place as part of a larger operation, primarily to maintain the combat effectiveness of committed units. The higher echelon headquarters directs when and where to conduct a relief and establishes the appropriate control measures. Normally, during the conduct of large-scale combat operations, the unit being relieved is defending. However, a relief may set the stage for resuming the offense. A relief may also serve to free the relieved unit for other tasks, such as decontamination, reconstitution, routine rest, resupply, maintenance, specialized training, or redeployment. Sometimes, as part of a larger operation, a commander wants an enemy force to discover the relief, because that discovery might cause an enemy to do something in response that is contrary to its interests, such as move reserves from an area where the friendly commander wants to conduct a penetration.