Since Bragg had not provided for a tactical reserve and the narrow ridgetop left no place for one, his defenses were only a thin crust. To seal off the breach, the Southern generals were placed on the horns of a dilemma. When they found Union troops on their flank, they had to pull regiments out of their defense line for a counterattack. This weakened the main line of resistance just as the Union brigades to their front were swarming up to the crest.