rear guard

基本解釋

These stubborn and skilful rear guard actions checked the impetuous German advance at all points , inflicting severe losses.
這幾場打得頑強(qiáng)而巧妙的后衛(wèi)戰(zhàn)，在各個方面都阻止了猛撲過來的德軍，使他們遭受嚴(yán)重的損失。
The remaining two alien formations fired upon this Covenant rear guard—energy beams cut their shields and blasted them to atoms.
其余的隊列繼續(xù)向圣約人艦隊的后衛(wèi)開火。能量束切開他們的護(hù)盾，把他們燒成原子。
nicolar2009.blog.163.com
Unnerved by sharp counterattacks delivered by the outnumbered Confederate rear guard, Hooker squandered his advantage by halting to erect defenses near the Chancellor farm.
受挫于數(shù)量不及自己的邦聯(lián)軍后衛(wèi)猛烈的反擊，Hooker 將軍平白浪費(fèi)了自己兵力上的優(yōu)勢而在 Chancellor 農(nóng)場駐軍建立防御工事。

And finally the rear guard, aka: the old farts.
FORBES: VOIP Tipping Point
One of several problems that delayed the formation of the new government was the rear guard action waged by the Shiite Fadila Party to hang onto the Oil Ministry, which it controlled under former Prime Minister Ibrahim al-Jafari.
NPR: Iraq Oil Minister Vows to Fight Corruption, Smuggling
What about the rear guard?
FORBES: VOIP Tipping Point

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.