Which type of fire involves firing down an enemy's line of approach, often causing maximum casualties?

Enfilade fire is a tactical method of shooting that targets an enemy's line of approach, which allows for a concentrated impact on forces as they attempt to advance. This type of fire is particularly effective because it engages troops in a linear formation, typically resulting in significant casualties. When weapons are positioned to deliver fire parallel to the enemy's movement, it maximizes the area of impact and the likelihood of hitting advancing personnel.

In contrast, other types of fire, such as frontal fire, would direct fire straight ahead rather than along the enemy’s path, potentially reducing effectiveness against advancing troops. Plunging fire involves shooting from a high point down onto a target area, which may not specifically target an enemy's line of advance. Grazing fire is characterized by being effective at a lower level where the projectile travels just above the surface, which may not achieve the same optimal engagement with forces moving in formation. Therefore, enfilade fire is uniquely suited to inflict the most damage when engaging an enemy on the move.