noun
1. : a defensive or delaying fight engaged in by a rear guard (as in covering the retreat of an army or the evacuation of a besieged garrison)
2. : an effort put forth by means of preventive or delaying measures or tactics and usually against great odds in defense of a threatened existing order or situation or in opposition to a proposed new departure
to be something of a brake, to perform a rearguard action, if you will, on inflationary trends — D.V.Brown
dissipate their influence in relatively ineffective rearguard actions designed to prevent particular regulatory measures — H.R.Bowen