Beachhead
A
beachhead is a
military term used to describe the line created when a unit (by sea) reaches a beach, and begins to defend that area of beach, while other reinforcements (hopefully) help out, until a unit large enough to begin advancing has arrived. Beachheads were very important in operations such as
D-Day, the
Korean War (especially at
Inchon), and the
Vietnam War, among many other examples.