A Game of Birds and Wolves: The Ingenious Young Women Whose Secret Board Game Helped Win World War II

by Simon Parkin

Finally, there was the introduction of Hedgehog, a bow-mounted anti-submarine weapon that could spray a volley of mortar rounds directly ahead of the ship, toward a suspected U-boat location. The name derived from the weapon’s appearance: the twenty mortar rounds were bunched together at a near-perpendicular angle, giving the appearance of a hedgehog’s spikes. The projectiles were primed to explode not by fuse but on contact, and entered the war just as the U-boat captains had become adept at evading depth charges. By increasing the strength of U-boat hulls so that they could withstand the pressure at 600 feet, a U-boat captain could now listen on the hydrophones for the roar of a warship overhead, and the telltale splash of the depth charges, and immediately increase to full speed, turning sharply while diving. During the time it took for the depth charge to fall, the U-boat would have disappeared. The Hedgehog enabled the explosives to be hurled ahead, while the U-boat was still within ASDIC contact, and before it could turn and dive.18

Hedgehog