The Marine Corps calls it Close Order Drill. Below is a quote from the Drill and Ceremonies Manual that gives some of the reason we still learn the march:
> The object of close order drill is to teach Marines by exercise to obey orders and to do so immediately in the correct way. Close order drill is one foundation of discipline and esprit de corps.Additionally, it is still one of the finest methods for developing confidence and troop leading abilities in our subordinate leaders.
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