The Mini Subs: Japan’s First Appearance at Pearl Harbor

There are few historic events more known in the United States than the December 7th, 1941 attack on Pearl Harbor. Even though there have been countless retellings and a myriad of movies and hours of news coverage, it may come as a surprise to learn that there are still aspects of the surprise attack that many people don’t know about. We’re not talking about major details, of course, like that it was a Japanese striking force that flew into the harbor or that the United States joined World War II immediately after; but smaller details, like the fact that the attack on Pearl Harbor can be said to have started a lot earlier than many think.

On that Sunday morning in the Pacific, a lot was going on and many details have been lost over the years and overshadowed by the devastation of the attack. Some of those missing details pertain to Japanese mini subs that were really at the vanguard of the Pearl Harbor assault.

Before the Planes

Japanese submariners

At around 0345 on the morning of December 7th, Quartermaster R.C. Uttrick spotted an unexpected sight from the deck of the minesweeper USS Condor. According to the sailor’s observation, he was looking at a periscope, despite the fact that there weren’t meant to be any submarines at Pearl Harbor that morning.

New to the Imperial Japanese Navy, the mini submarine was a last-minute addition to the Pearl Harbor attack plan. Their purpose was to assist the fighters and bombers in destroying the American fleet with their own assortment of torpedoes. The plan was met with concern from the pilots, who believed that all they might do was potentially give away the plan of the attack, especially if any of the mini subs was captured and its crew interrogated.

The first of the mini subs entered Pearl Harbor, its presence threatening to give away Japan’s presence in the area. Just as many had feared, the sub didn't go unnoticed and just before 0700, the small vessel was sunk by the destroyer USS Ward. Technically the first casualty of the Pearl Harbor attack was suffered by Japan but unfortunately, that was no use to the men stationed at Pearl Harbor.

A Missed Warning

Japanese mini sub recovered from Pearl Harbor

The Ward quickly reported on the situation, advising of the submarine it observed near the mouth of the harbor. Though the report—which may have given the United States an hour lead on the incoming Japanese fighters—was sent, it never made it to the appropriate leaders.

At 0755, the attack began. In the air, fighters and bombers did the bulk of the damage, dropping torpedoes that struck the vessels at Battleship Row; but there was another element that’s rarely talked about. The remaining four mini subs tried to assist but were all quickly disabled, some by American ships and others due to mechanical failure.

By the end of the attack, the mini submarines had served no purpose. It’s believed that none of the four subs that engaged in the surprise attack—the fifth was disabled and drifted to the east coast of Oahu—did any damage to the battleships, although in Japan, one was credited with sinking the USS Arizona.