“挖战壕”的英语？

在三角洲挖战壕有什么用?What is the use of digging trenches in the Delta?他们在挖战壕以免受炮火的袭击.They were digging trenches to shelter the men from gunfire.他们还来不及挖战壕就受到了攻击.They were attacked before they had time to dig in....