A feigned retreat is a military tactic whereby an army will pretend to withdraw

Withdrawal (military)

A withdrawal is a type of military operation, generally meaning retreating forces back while maintaining contact with the enemy. A withdrawal may be undertaken as part of a general retreat, to consolidate forces, to occupy ground that is more easily defended, or to lead the enemy into an ambush...

 or that they have been routed

Rout

A rout is commonly defined as a chaotic and disorderly retreat or withdrawal of troops from a battlefield, resulting in the victory of the opposing party, or following defeat, a collapse of discipline, or poor morale. A routed army often degenerates into a sense of "every man for himself" as the...

 in order to lure an enemy into a position of vulnerability. Feigned retreats are one of the more difficult tactics for an army to undertake, and require well-disciplined soldiers. This is because if the enemy presses into it, undisciplined troops will lose coherence and the rout will become genuine.

This tactic was well known in antiquity. Herodotus

Herodotus

Herodotus was an ancient Greek historian who was born in Halicarnassus, Caria and lived in the 5th century BC . He has been called the "Father of History", and was the first historian known to collect his materials systematically, test their accuracy to a certain extent and arrange them in a...

 reports that the Spartans

Sparta

Sparta or Lacedaemon, was a prominent city-state in ancient Greece, situated on the banks of the River Eurotas in Laconia, in south-eastern Peloponnese. It emerged as a political entity around the 10th century BC, when the invading Dorians subjugated the local, non-Dorian population. From c...

 employed it at the Battle of Thermopylae

Battle of Thermopylae

The Battle of Thermopylae was fought between an alliance of Greek city-states, led by King Leonidas of Sparta, and the Persian Empire of Xerxes I over the course of three days, during the second Persian invasion of Greece. It took place simultaneously with the naval battle at Artemisium, in August...

 to defeat a force of Immortals

Persian Immortals

The "Immortals" was the name given by Herodotus to an elite force of soldiers who fought for the Achaemenid Empire. This force performed the dual roles of both Imperial Guard and standing army during the Persian Empire's expansion and during the Greco-Persian Wars...

.