St. John in Hong Kong provided emergency medical service to the British Hong Kong military during the Japanese invasion of Hong Kong in December 1941 (World War II). Dr. Wai-Cheung Chau (周懷璋,1893–1965), was present in the battle at Magazine Gap as a medical officer of St John Ambulance. While he was in a car, the person sitting next to him was killed and he was wounded by a bullet through his lung. The blood clot in his lung was with him for the rest of his life.