What is the command given to close the interval while marching?

The command to close the interval while marching is "CLOSE, MARCH." This command instructs troops to reduce the space between themselves and the individual in front of them, thereby bringing them closer together in formation. The use of the term "CLOSE" directly conveys the action that needs to be taken, which is to minimize the distance or gap in marching formation.

Contextually, each command has a specific purpose. "CLOSE UP" typically serves as an instruction to ensure tighter formations but may not specifically indicate marching. "REDUCE INTERVAL" is more generalized and may not specify the action associated with marching. "HALVE INTERVAL" implies a specific measurement reduction, which might not effectively communicate the immediate need to close the gaps during movement. Therefore, "CLOSE, MARCH" precisely communicates the action required for soldiers to maintain disciplined formation while on the move.