The Japanese began developing midget submarines in the early 1930s. The Type "A" was perhaps the most advanced midget submarine in service with any navy during World War II. They were designed to be carried into a forward area by specially configured surface ships or submarines. Five Type "A" subs were involved in the attack on Pearl Harbor, but all were lost. The HA-19 struck a reef and drifted ashore. Her commanding officer was captured and became the first Japanese prisoner of war.
Sea - Military - Submarines