In machine gun defensive operations, what is the purpose of the Final Protective Line (FPL)?

The purpose of the Final Protective Line (FPL) in machine gun defensive operations is to provide grazing fires across a unit's frontage. The FPL is designed as a last defensive measure to deliver effective and sustained fire against enemy forces attempting to breach defensive positions. It establishes a predetermined line where machine guns will focus their fire to create a lethal area that can significantly reduce or eliminate the advancing enemy.

This line is critical because it allows for effective overlapping fields of fire, maximizing the defensive capabilities of the machine guns and contributing to the overall effectiveness of the unit's defense. By creating grazing fire, where the projectiles travel just above the ground to target enemy personnel, the FPL ensures that enemy forces are engaged before they can get too close to friendly troops or key terrain.

The other options relate to different tactical concerns but do not reflect the primary function of the FPL in supporting defense through effective fire. The FPL is specifically about providing the ground-based fire necessary to disrupt and halt enemy advances effectively.