降伏【こうふく】
surrender, capitulation, submission, yield
伏線【ふくせん】
foreshadowing, preparation, precautionary measures
伏兵【ふくへい】
ambush, troops in ambush, unexpected opposition, unexpected obstacle
潜伏【せんぷく】
concealment, hiding, ambush, incubation, latency, dormancy
待ち伏せ【まちぶせ】
ambush, lying in wait for an ambush