rearguard

• rear guard, rear-guard

rear +‎ guard. Attested in The Song of Roland circa 1150 (rereguarde)

• IPA^(key): /ˈɹɪəɹˌɡɑɹd/

rearguard (plural rearguards)

1. (military) The rearmost part of a force, especially a detachment of troops that protect the rear of a retreating force.
2. (soccer) The defence, collectively the defenders.
   • 2011 January 22, Phil McNulty, “Aston Villa 1 - 0 Man City”, in BBC‎:

     Mancini's side only showed enough ambition when it was too late and by then battle lines were drawn as James Collins and former City captain Richard Dunne fought a magnificent rearguard action at the heart of Villa's defence.

• Usually used attributively.

• vanguard