The pincer movement or double envelopment is a basic element of military strategy which has been used, to some extent, in many wars, and is considered to be the consummate military maneuver, executed by Hannibal at the Battle of Cannae in 216 BC, over 2,200 years ago. This maneuver was also later effectively used by Khalid ibn al-Walid at the Battle of Walaja in 633 AD, and by Daniel Morgan at the Battle of Cowpens over 1,100 years later. An earlier form of pincer movement was also described by the Chinese military theorist Sun Tzu in the 6th century BC, and possibly used at the Battle of Marathon in the 5th century BC.
Hannibal's double envelopement at the Battle of Cannae in 216 BC is viewed by military historians as one of the greatest battlefield maneuvers in history, and is cited as the first successful use of the pincer movement to be recorded in detail.
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.
A double envelopment by definition leads to the attacking army facing the enemy in front, on both flanks, and in the rear. If the attacking pincers link up in the enemy's rear, the enemy is encircled. Such battles often end in surrender or destruction of the enemy force, although the encircled force can attempt a breakout, attacking the encirclement from the inside in order to escape, or a friendly external force can attack from the outside to open up an escape route for the encircled force.