What is the first step to determine how many turns of traverse to use?

Determining the total mils of the target is crucial because it directly impacts how the fire control has to be adjusted to effectively engage the target. The total mils represent the angular size of the target, which helps in calculating how the rounds should traverse to ensure coverage over the target area. By knowing how wide the target is in mils, one can assess the necessary adjustments needed for accurate firing. This step forms the foundation for further calculations, such as how many turns of traverse are necessary to appropriately align the weapon system with the target.

Understanding the width of the target, the distance from the forward observer or firing line to the gun, and the number of intervals are all important, but they build on the knowledge of the total mils required to effectively target an area. Thus, determining the total mils of the target serves as the first and essential step in the process.