Britannic was most likely sunk by a mine laid by the German minelaying submarine SM U-73 on 21 October 1916, a month before the hospital ship struck it. A torpedo explanation had obvious propaganda value because Britannic was a hospital ship. The blast damaged bulkheads and the boiler-room tunnel, while the watertight door between boiler rooms six and five failed to shut fully. As the ship listed, open portholes admitted water above the protection intended by her compartmentation. Nearby vessels responded quickly, limiting loss of life despite the speed of the sinking. Foresight arrived after several smaller rescuers, but her captain was senior enough to help organize the response. The loss also shows how a mine could make an apparently safe area dangerous long after being laid.
Chapter · 31:37-36:27
Foresight at Britannic's sinking
Foresight arrived to help organize the response after HMHS Britannic struck a mine, illustrating the enduring danger of mine warfare.