Speed as battle-line control

What does a small speed difference between battle lines actually change?

Speed matters because it lets one battle line dictate range, angle, and whether it can force a crossing-the-T position.

If both battle lines move at the same speed, crossing the T depends heavily on the angle of approach. A four-knot advantage lets the faster line overtake, choose the range, and determine how the action develops. The tactical value of speed lies in control of the engagement, not the number on a specification sheet.