The attack on Pearl Harbor that catapulted the United States into World War II was a devastating blow, and forced the hand of the US to join the Second World War. The attack killed 2,403 US personnel, including 68 civilians, and destroyed or damaged 19 US Navy ships, including 8 battleships. More than 1,000 were also wounded.

There were two key factors in Japan’s Military presence that led to Japan’s success, and those were their shallow-water aerial torpedoes and their fleet’s capability to elude discovery.

Because of Pearl Harbor’s shallow floor, Japan’s standard torpedoes when fired, would just hit the bottom of the ocean floor and have no effect, so for months leading up to the attack, Japanese designers had secretly been creating torpedoes with fins that could perform specifically in shallow water.

Japanese torpedo boat Kasasagi

By the fall of 1941, they had perfected the weapon, and all they had to do was carry it to the American naval base unnoticed. Japan’s fleet of ships managed to stay undetected throughout the journey to Hawaii that began in November of 1941, by taking a far-northern course beyond the range of island-based US patrol planes, and away from shipping lanes.

In the Sea

The Torpedoes:

Type 91 Mod 3 – It had a heavier explosive charge and a thinner air vessel and anti-roll stabilizers than the previous mod versions. It was first delivered in April 1941 and this torpedo was heavily modified for use in shallow waters by attack planes at Pearl Harbor. This torpedo had a 2 kilometre range.

Japanese Submarine Crew

Type 97 Modified – Designed for Midget Submarines and was essentially a smaller version of the Type 93 and Type 95 torpedoes. Only about 100 were made, and were used operationally only during the Pearl Harbor attack. The Type 97 had a 5.5 kilometre range.

The ships:

Japanese forces in the water were very strong, and consisted of two heavy cruisers, 35 submarines, two light cruisers, nine oilers, two battleships, and 11 destroyers.

The Submarines:

The “Type A” Ko-hyoteki was a class of Japanese midget submarines that had a crew of two men, used during the Pearl Harbor bombing. Five of these boats participated in the Pearl Harbor attack, with only two making it into the harbor. Each were each armed with two 450 mm specially designed Type 97 torpedoes, one in muzzle-loading tubes, and one above the other at the bow. These submarines also had a demolition charge which it has been suggested was large enough to enable the submarine to be used as a suicide weapon, but there is no evidence that it was ever used as one.

Japanese Airplane

In the Air

The Planes:

The Japanese strike force consisted of 353 aircraft launched from four heavy carriers.

The planes used in the attack were specifically 131 strong of the Aichi 3A2, Val Type 99, single-engine dive bombers, 79 of the Mitsubishi A6M2 Zeke or Zero Model 11 Carrier-borne fighter, and 143 NakajimaB5N2 Kate Type 97, Model 12 Single-engine torpedo bombers.

The attack also consisted of two heavy cruisers, 35 submarines, two light cruisers, nine oilers, two battleships, and 11 destroyers.

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