Line formation

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.

An infantry battalion would form "in line" by placing troops in several ranks, ranging in number from two to five, with three ranks being the most common arrangement. Each rank was approximately half a metre apart from the next, and soldiers in a rank were positioned closely to each other (usually within arm's length), with just enough room to present their weapons, fire, and reload. The line formation required that the troops be well-drilled and constantly supervised by officers and non-commissioned officers (NCOs).

In 17th- and 18th-century European armies, NCOs were positioned to the rear of the line. They were equipped with long polearms, which they used to "dress" or arrange the ranks, a practice which included pushing down the weapons of any soldier who was aiming too high, as well as ensuring that the rank remained well-organized and correctly placed. Movement in line formation was very slow, and unless the battalion was superbly trained, a breakdown in cohesion was virtually assured, especially in any kind of uneven or wooded terrain. As a result, line was mostly used as a stationary formation, with troops moving in columns and then deploying to line at their destination.

...
Wikipedia