A forlorn hope Meaning, Definition & Usage

Definitions
  1. D. verloren hoop, prop., a lost band or troop; verloren, p.p. of verliezen to lose + hoop band; akin to E. heap. See For-, and Heap. (Mil.), a body of men (called in F. enfants perdus, in G. verloren posten) selected, usually from volunteers, to attempt a breach, scale the wall of a fortress, or perform other extraordinarily perilous service; also, a desperate case or enterprise.

Webster 1913