bridgehead
noun [ C ] uk/ˈbrɪdʒ.hed/ us/ˈbrɪdʒ.hed/
桥头阵地，桥头堡（在敌占区内夺取的据点）
a good position that an army has taken in enemy land, from which it can attack the enemy more effectively
The advance troops established a bridgehead early in the fighting. 先遣部队在战斗刚开始时就建立了桥头堡。
Compare: beachhead