What is meant by "passage of lines" in military terms?

The term "passage of lines" in military terminology specifically refers to the action of one unit or element moving through the positions of another friendly unit. This maneuver allows the second unit to continue its operations while the first unit advances, retreats, or repositioning itself for an operational advantage.

This concept is particularly important in operations where units must maintain momentum or flexibility in response to evolving battlefield conditions. Successfully executing a passage of lines requires coordination, communication, and tactical planning to minimize confusion and maintain the integrity of both units involved in the maneuver.

In contrast, engaging the enemy while moving forward, providing early warning before engagement, or establishing a defensive line pertain to different tactical aspects and objectives of military operations, but do not specifically define the maneuver of one unit passing through another's positions.