The "indirect" approach into battle also allowed Napoleon to disrupt the linear formations used by the allied armies. As the battle progressed, the enemy committed their reserves to stabilize the situation, Napoleon would suddenly release the flanking formation to attack the enemy. His opponents, being suddenly confronted with a new threat and with little reserves, had no choice but to weaken the area closest to the flanking formation and draw up a battle line at a right angle in an attempt to stop this new threat. Once this had occurred, Napoleon would mass his reserves at the hinge of that right angle and launch a heavy attack to break the lines. The rupture in the enemy lines allowed Napoleon's cavalry to flank both lines and roll them up leaving his opponent no choice but to surrender or flee.