rear-guard

基本解释

Recalling the care his quarry had displayed in defeating the crypt traps, he ordered a three-elf rear guard to follow behind.
再次提醒那些被追捕者击败了陷阱之后，加拉隆命令一个由三名精灵组成的后卫小队跟随。
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A little behind them, there sat on the trunk of a cannon, Nesvitsky, who had been despatched by the commander-in-chief to the rear-guard.
在他们背后几步路远的地方，由总司令派往后卫部队的涅斯维茨基正坐在炮架尾部。
At ten o'clock in the morning of the 2nd of September the only troops left in the Dorogomilov suburbs were the regiments of the rear-guard, and the crush was over.
到九月二日上午十点钟为止，在多罗戈米洛夫郊野只剩下后卫部队了。

You and your lawyers want to thrash this out, case by case, fighting a trench-warfare, rear-guard action?
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Even now it is waging a rear-guard action to undo the easing that the FASB promulgated in April.
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The judge's clumsy move is a rear-guard action against a basic freedom.
FORBES: Fact and Comment

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.