7-126. In figure 7-15 the lead division is the decisive operation and the trail division follows and supports. The lead division engages and destroys enemy security forces. +The trail division with the follow and support mission eliminates bypassed enemy forces, secures key terrain, screens the flanks of the corps, and conducts minimum-essential stability tasks, if required. It also provides one IBCT as the corps reserve. Depending upon the mission variables, the trail division may conduct a forward passage of lines through the lead division and conduct the corps decisive operation. In this example, the corps reserve is an IBCT positioned in a heavy pickup zone in the corps AO. The corps provides aviation support obtained by tasking the combat aviation brigades (CABs) of its subordinate divisions and coordinates with the United States Air Force (USAF) and theater aviation brigade to air move or air assault the reserve upon commitment. A corps normally uses PLs to control an operation as its divisions advance. A corps transitions to a deliberate operation if the lead division encounters a prepared enemy defense. A corps conducts hasty operations and exploits any favorable situations if an enemy is unprepared or defending weakly.