Q-ships
Q-ships, also known as Q-boats, decoy vessels, special service ships, or mystery ships, were heavily armed merchant ships with concealed weaponry, designed to lure submarines into making surface attacks. This gave Q-ships the chance to open fire and sink them.
They were used by the British Royal Navy (RN) and the German Kaiserliche Marine during the First World War and by the RN, the Kriegsmarine and the United States Navy during the Second World War (1939–45).
A solution to this was the creation of the Q-ship, one of the most closely guarded secrets of the war. Their codename referred to the vessels' home port, Queenstown, in Ireland.[2] These became known by the Germans as a U-Boot-Falle ("U-boat trap"). A Q-ship would appear to be an easy target, but in fact carried hidden armaments. A typical Q-ship might resemble a tramp steamer sailing alone in an area where a U-boat was reported to be operating. By seeming to be a suitable target for the U-boat's deck gun, a Q-ship might encourage the U-boat captain to make a surface attack rather than use one of his limited number of torpedoes. The Q-ships' cargoes were light wood (balsa or cork) or wooden casks, so that even if torpedoed they would remain afloat, encouraging the U-boat to surface to sink them with a deck gun. The crew might even pretend to "abandon ship". Once the U-boat was vulnerable, the Q-ship's panels would drop to reveal the deck guns, which would immediately open fire. At the same time, the White Ensign (Royal Navy flag) would be raised. With the element of surprise, a U-boat could be quickly overwhelmed.