The rearmost part of a force, especially a detachment of troops that protect the rear of a retreating force
In a battle, the rearguard is a group of soldiers who protect the back part of an army, especially when the army is leaving the battle
If someone is fighting a rearguard action or mounting a rearguard action, they are trying very hard to prevent something from happening, even though it is probably too late for them to succeed. Mr Urban looks increasingly like someone fighting a rearguard action to keep their job