The line formation is a standard tactical formation which was used in early modern warfare. It continued the phalanx formation or shield wall of infantry armed with polearms in use during antiquity and the Middle Ages.

The line formation provided the best frontage for volley fire, while sacrificing maneuverability and defence against cavalry. It came to the fore during the Age of Reason, when it was used to great effect by Frederick the Great and his enemies during the Seven Years' War.