Close interval Procedures
To ensure that each member understands the number of steps to take, the squad leader should command Count, OFF before giving any commands that cause the squad to change interval. Members do not raise their arms when changing interval.
To obtain Close Interval from Normal Interval, the command is Close Interval, MARCH. On the command of execution MARCH, the right flank man (number one man) stands fast. All men to the left of the number one man execute Right Step March, take one step less than their number (for example, number two man takes one step), and Halt.
Video:
http://www.pdf-archive.com/2014/01/22/army-tc-3-21-5/army-tc-3-21-5.pdf
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