保垒

例句：

1. 1. The ancient fortress was a symbol of the kingdom's strength.
   这个古老的要塞是王国力量的象征。
2. 2. The soldiers fought bravely to defend their fortress against the enemy.
   士兵们勇敢地保卫他们的要塞，抵抗敌人。
3. 3. The citadel was a place of refuge for those fleeing from the war.
   这个要塞是那些逃离战争的人的避难所。