What does "deflection" refer to in mortar firing?

Deflection refers to the modification of the lateral aim to hit the target. In mortar firing, achieving accuracy requires adjustments not only in range (distance) but also in the lateral direction—essentially left or right adjustments to ensure the projectile lands on target. Deflection accounts for various factors that can affect the trajectory of a mortar round, such as terrain differences or approaching the target from a different angle.

This adjustment is crucial because a mortar round that is fired with perfect range but incorrect lateral aim will miss the target, demonstrating that lateral adjustments are an essential aspect of precision in indirect fire. While factors like wind speed and elevation may also play important roles in mortar fire, they pertain to other aspects of the firing process and don't specifically define the term "deflection."