The pincer movement (double envelopment) is a basic element of military strategy which has been used, to some extent, in nearly every war. The maneuver is mostly self-explanatory; the flanks of the opponent are attacked simultaneously in a pinching motion after the opponent has advanced towards the center of an army which is responding by moving its outside forces to the enemy's flanks, in order to surround it. At the same time, a second layer of pincers attacks on the more extreme flanks, so as to prevent any attempts to reinforce the target unit.
Most infantry combat, on every scale, is based in some fashion on this military tactic and it is commonly used by aircraft as well. It was vaguely described in Sun Tzu's The Art of War, but he argued that it was best to allow the enemy a path to escape, as he felt the target army would fight with more ferocity when completely surrounded. However, the pincer is commonly employed in modern warfare.