The steady, regular marching step was a marked feature of Roman legions.
For troops who march in an irregular and disorderly manner are always in great danger of being defeated.
If they exceed this pace, they no longer march but run, and no certain rate can be assigned.
[1]Military marching of foot formations into a battle was a common practice in most European countries for centuries, and was even carried over into the new world as recently as the American War of Independence.
Most Western Bloc nations currently have similar quick marching styles of lifting their legs in a natural or casual manner.