堡垒

fort;fortress;bulwark;stronghold;blockhouse;citadel;castle
～是最容易从内部攻破的。A fortress is most vulnerable when attacked from within./反对种族隔离运动的～bulwark of anti-apartheid movement/殖民主义的最后～last stronghold(or citadel) of colonialism/革命的～ bulwark of revolution/顽固～ stronghold of conservatism/～政策policy of blockhouse warfare/～主义policy (or principle) of blockhouse warfare/～主义的战略strategy of building blockhouses