Pincer movement

The pincer movement, or double envelopment, is a military maneuver in which forces simultaneously attack both flanks (sides) of an enemy formation. The name comes from visualizing the action as the split attacking forces "pinching" the enemy.

The pincer movement typically occurs when opposing forces advance towards the center of an army that responds by moving its outside forces to the enemy's flanks to surround it. At the same time, a second layer of pincers may attack on the more distant flanks to keep reinforcements from the target units.

A full pincer movement leads to the attacking army facing the enemy in front, on both flanks, and in the rear. If 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, but the encircled force can try to break out. They can attack the encirclement from the inside to escape, or a friendly external force can attack from the outside to open an escape route.

Sun Tzu, in The Art of War (traditionally dated to the 6th century BC), speculated on the maneuver but advised against trying it for fear that an army would likely run first before the move could be completed. He argued that it was best to allow the enemy a path to escape (or at least the appearance of one), as the target army would fight with more ferocity when completely surrounded, but it would lose formation and be more vulnerable to destruction if shown an avenue of escape.

The maneuver may have first been used at the Battle of Marathon in 490 BC. The historian Herodotus describes how the Athenian general Miltiades deployed 10,000 Athenian and 900 Plataean hoplite forces in a U-formation, with the wings manned much more deeply than the centre. His enemy outnumbered him heavily, and Miltiades chose to match the breadth of the Persian battle line by thinning out the centre of his forces while reinforcing the wings. In the course of the battle, the weaker central formations retreated, allowing the wings to converge behind the Persian battle line and drive the more numerous, but lightly armed Persians to retreat in panic.

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