Rearguard

A United States Marine providing rear security to his unit during a simulated patrol in 2009

A rearguard or rear security is a part of a military force that protects it from attack from the rear, either during an advance or withdrawal. The term can also be used to describe forces protecting lines, such as communication lines, behind an army.^[1] Even more generally, a rearguard action may refer idiomatically to an attempt at preventing something though it is likely too late to be prevented; this idiomatic meaning may apply in either a military or non-military context.^[2]

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Oxford English Dictionary:
- rearguard n.1.b: A body of troops detached from the main force to bring up and protect the rear, esp. in the case of a retreat. Also fig. and in extended use."
- "rear guard, n.2: Chiefly Brit. The guard at the rear of a railway train."
^ Cite error: The named reference idiom was invoked but never defined (see the help page).

[1] Oxford English Dictionary:
rearguard n.1.b: A body of troops detached from the main force to bring up and protect the rear, esp. in the case of a retreat. Also fig. and in extended use."

"rear guard, n.2: Chiefly Brit. The guard at the rear of a railway train."

[2] rearguard n.1.b: A body of troops detached from the main force to bring up and protect the rear, esp. in the case of a retreat. Also fig. and in extended use."

[3] "rear guard, n.2: Chiefly Brit. The guard at the rear of a railway train."

[idiom-2] Cite error: The named reference idiom was invoked but never defined (see the help page).

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