Infantry Drills

5-140: Mounted Security Halt

Previous: 5-139: Perimeter Defense

5-140. The platoon employs the coil, herringbone, and triangle “Y” formations to
maintain 360-degree security when stationary.

5-141. The coil provides all-round security and observation when the platoon is
stationary. The patrol also uses the coil for tactical refueling, resupply, and issuing patrol orders. When in a coil, leaders post security. (See figure 5-20.)

Figure 5-20. Coil formation

5-142. The patrol leader uses the herringbone and triangle during temporary halts or when getting off a road to allow another unit to pass. It lets the patrol move to covered and concealed positions off a road or from an open area and establishes all-round security without issued detailed instructions. The truck commander repositions their vehicles as necessary to take advantage of the best cover, concealment, and fields of fire. Fire team members dismount and establish security. (See figures 5-21 and 5-22.)

Figure 5-21. Herringbone formation
Figure 5-22. Triangle Y formation

Next: 5-143: Actions At Halts

Go Back To: U.S. Army FM 3-21.8: The Infantry Rifle Platoon and Squad