Early submarines often surfaced and used deck guns because torpedoes were scarce, expensive, and carried in limited numbers. A disguised Q-ship waited until the submarine came close and ordered surrender before revealing hidden weapons and opening fire. German crews responded by attacking merchant-looking ships from concealment rather than exposing themselves to another ambush. The tactic therefore helped drive escalation toward unrestricted submarine warfare, after which many Q-ships lost their special opportunity and served more conventionally as convoy escorts.
Chapter · 2:54:24-2:56:10
Q-ships change the submarine warning calculus
Disguised Flower-class sloops exploit submarines that surface to conserve torpedoes, but the tactic encourages attackers to torpedo merchantmen without warning.