Winston Churchill, father of so many of the deceptions and ruses of 20th Century warfare, invented the idea of Q-ships in 1914. As First Lord of the British Admiralty, Churchill signaled the Commander-in-Chief, Portsmouth, Admiral Sir Hedworth Meux, on 26 November 1914: "It is desired to trap the German submarine which sinks vessels by gunfire ... A small or moderate sized steamer should be taken up and fitted very secretly with two twelve-pounder guns in such a way that they can be concealed with deck cargo or in some way in which they will not be suspected. She should ... have an intelligence officer and a few seamen and two picked gunlayers who should all be disguised. If the submarine stops her she should endeavor to sink her by gunfire. The greatest secrecy is necessary to prevent spies becoming acquainted with the arrangements."
Bridgland's "Sea Killers in Disguise" tells how, from 1915-1917, about 200 British ships were converted to Q-ships. The Q-ships were large enough to be appealing U-boat targets, but not quite so large as to warrant a scarce German torpedo. U-boats mostly attacked on the surface, after challenging their targets to stop. The Q-ships were "a strategic lure, a tactical bait, and a deadly hook," to catch the German "U-fish," whose secret weapon was deception. Q-ship camouflage screens concealed weapons that included depth charges, torpedoes, and 4-inch guns. When stopped by a U-boat, the well-drilled Q-ship crew would conduct the "panic tactic"-pretending to abandon ship, while hidden gun crews dropped the screens hiding the Q-ship's armaments. The approaching U-boat would be blown out of the water. At least that was the theory.
Q-ships fought over seventy duels with U-boats, and sunk eleven to fourteen (about eight percent of the 145 U-boats sunk during the Great War), with about 25 to 30 Q-ships sunk by the U-boats (about fifteen percent of the Q-ship fleet; historians differ on the various numbers). Q-ship effectiveness in the Great War, numerically modest, had greater psychological impacts. Q-ships damaged some of the U-boats they failed to sink. The Q-ship deceptions deterred all U-boat skippers; the most helpless steamer could turn out to be a "trap ship," as the Germans called them; probably more than one an innocent merchantman was spared by the overly-suspicious U-boat commanders. Memories of the Q-ships even inspired caution in the next generation of U-boat skippers during World War Two.
The sheer numbers of the Q-ship engagements provided the German U-boatmen useful counter-deception indicators. U-boat survivors of Q-ship duels, and letters from captured U-boat crewmen soon compromised the basic Q-ship secrets. U-boat captains approached even the most innocent steamers ready to sink them. The "panic tactic" lost its novelty. In January 1917 German naval strategy changed to unrestricted submarine warfare and the U-boats attacked submerged. The Q-ship deception had run its course. No longer obliged to surface and challenge a target, U-boats attacked without warning, rendering Q-ship deceptions useless. Convoying (the best anti-submarine tactic) made individual decoys, like the Q-ships, pointless. Bridgland's "Sea Killers in Disguise" provides a superb reference to these decoy and deception trap ships in the Great War, offering lessons for today's naval commanders confronting camouflaged arms and drug runners, terrorist suicide ship bombs, and other modern asymmetric naval threats based on denial and deception.