游击队在山顶建立了临时防御工事来监视敌人动向。

The guerrillas set up ___redoubts on the hilltop to monitor enemy movements.

这个小村庄成为了战争期间他们的最后避难所。

The small village became their final ___redoubt during the war.

这所大学长期以来一直是自由思想的堡垒。

This university has long been a ___redoubt of liberal thinking.