Amphibious Assault Craft – Invasion from the Sea

Any game that depicts an invasion of Japanese troops should involve the sea to some extent, unless the scenario is deep in China. Unusual for their time and ground-breaking landing craft like the Shohatsu and Daihatsu are worth including in games involving ground troops, alongside amphibious tanks like the SR-II Ro-Go, Type2 Ka-Mi, Type3 Ka-Chi, and Type4 To-Ku.

Amphibious Assault:

The ocean surrounding the Japanese islands has always been a deterrent to foreign invasion, but also an obstacle to Japan’s imperial ambitions. When Japan was making plans for the conquest of Asia, one of the first issues that needed to be resolved was the difficulty of transporting troops to foreign shores. Other concerns such as the ability for airplanes to travel long distances with limited fuel were hurdles as well, but a reliable and effective way of getting boots on the ground was key to any invasion.

Westerners are very familiar with the massed assault of Allied amphibious craft at Normandy on “D-Day”, but less know that the Imperial Japanese were among the first nations to pioneer and rely heavily on such amphibious landings. The use of Shohatsu and Daihatsu landing craft were instrumental in the “Asian Blitzkrieg” by Japan in the opening days of World War 2, and every bit as important if not more so than Japan’s use of aircraft carriers to attack Pearl Harbor. The world had to that point not seen mass amphibious landings like those conducted by Japan. The British, U.S., Dutch, and Chinese were fully unprepared for the wave of troops that came at them from the sea, often from unexpected directions.

Japan’s use of “marines” was not new to the time immediately preceding WW2 and dates back to the 1800s. However it is during the Second Sino Japanese War, and WW2 that followed, where Japanese amphibious landings and the equipment and vehicles to support them were perfected. Some of those vehicles are described below.

This woodblock painting depicts Japanese Naval Landing Forces during the 1875 Ganghwa Island incident in Korea.

Landing Craft:

When the Shohatsu-class landing craft first appeared a decade prior to WW2, they were unlike anything seen before. Prior to the Shohatsu, most boats used for landing purposes were little more than small boats and dinghies used by marines to board other ships or pull up alongside docks. The Shohatsu was designed to carry 35 men or up to 3.5 tons of cargo ashore in places least expected by the enemy. It had a provision for a single defensive machine gun. Later the Daihatsu landing craft was developed by 1937 to address the shortcomings of the Shohatsu craft.  It had a bow ramp that could be lowered to disembark up to 10 tons of cargo upon riding up onto a beach, and could even carry armored vehicles like the Type95 Ha-Go. The U.S. did not miss these innovations, and after reviewing photos of a Daihatsu landing craft, the ramp feature was adopted by the lead American landing craft designer (who previously had some similar drop ramp designs that had not been widely implemented). The Daihatsu landing craft could mount 2 light machine guns or 2-3 25mm/60 AA guns, though the latter were often not mounted in favor of space for cargo and soldiers. A plywood, unarmored version of the Daihatsu also existed due to a steel shortage in Japan post 1942.

Amphibious Tanks:

Perhaps the most interesting of Imperial Japan’s vehicles during WW2 were their amphibious tank designs which were unique and heavily inspired by the Naval focus of Japan. The Type2 Ka-Mi is well-known as a dedicated amphibious tank with removable “pontoon” that make it appear more like a small tracked gunboat than a tank when attached. While it came a bit too late to be effective in World War 2, the design allowed it to be a versatile and seaworthy tank unlike the experimental amphibious tanks of other nations. By the time it was deployed in battle Japan’s “invasion” phase had ended in favor of defense, however, severely limiting its use.

More creative use of the Type2 Ka-Mi against unsuspecting opponents (from behind a U.S. landing party) or on the coasts of Southeast Asia where Japan lacked proper tank support against Commonwealth forces late in the war would have potentially seen better utilization of the Ka-Mi. These scenarios could be explored in games. As it was deployed in reality it ended up waiting behind berms or otherwise buried in hull down positions of defense on Pacific Islands, a complete “waste” of its amphibious capabilities. In some cases the hull-down Ka-Mi were recorded as being destroyed before entering combat (before they could be manned for defense).

In the only recorded amtank vs. amtank battle cited by Ralph Zumbro in his book ‘Tank Aces’, several Ka-Mi tanks were engaged by a near equal force of U.S. LVTs, and whether by surprise or otherwise were taken out at Leyte by the LVTs. This account is in doubt, however since the Ka-Mi tanks were destroyed after landing on shore (from a transport as pictured below) where U.S. forces were already present. A differing account states otherwise:

 “When the Japanese tanks attempted to land on Leyte, they were told that the beaches they were landing on were still in Japanese hands. When the Japanese tanks and their transport ship were fired upon they assumed it was friendly fire and did not return fire. The transport ship was sunk, but was able to launch 8 of its 10 tanks, of which two were sunk in the water and five were destroyed on land while disembarking, and one was abandoned. There is no record of LVT tanks actually destroying Ka-Mi tanks. Rather they were destroyed by U.S. artillery guns.” (Credit: Shinhoto)

Since the armor of the LVT-1s was very similar to that on the Ka-Mi amtanks, and the Ka-Mi’s armament a superior tank gun in addition to machine guns (the LVT-1’s had machine guns only), the first account by Zumbro, also cited by Zaloga via Zumbro, is worth questioning, and at least one can conclude that the U.S. forces had surprise / initiative.

Also covered here at the Ikazuchi site are the SR-II Ro-Go and Type3 Ka-Chi amphibious tanks, both interesting designs which are not recorded as being deployed or having seen battle for different reasons, but are interesting nonetheless.

Type2 Ka-Mi amtanks on the deck of a transport ship

Submarine-launched assault vehicles:

Among the most interesting and unique seaborne vehicles from Japan were submarines that could be used to launch amphibious vehicles like the Type4 Ka-Tsu (carried externally with water-tight engine seals) or even the M6A Seiran attack floatplane (carried folded in a hangar inside a submarine), both of which were production vehicles. There were powerful manned torpedoes akin to “kamikaze” planes known as “Kaiten” which could piggy-back on a submarine as well and were like small submarines in their own right.

Although the manned torpedo Kaiten did see battle, a fact which was covered up by the U.S. military for years (see the book “Kaiten“), the Seiran and Ka-Tsu were late war projects which were tested and ready but not tried in battle for their “suprise attack” capability before the war ended.

While the M6A Seiran planes were carried inside an I-400 class submarine, the Type4 Ka-Tsu amphibious vehicle actually rode piggy-back like a kaiten, as seen in the image below. Thier engine bays were water tight, and the tracked vehicles could travel for hundreds of miles attached to the back of a submarine before being deployed to deliver supplies along with surprise attack capability as they carried twin torpedoes and two heavy machine guns each.

Gun Boats / Assault Craft:

Amphibious landings meant vulnerability to attack, as anyone familiar with D-Day knows. Unlike along the coast of Normandy, the Japanese had established some zones of naval superiority, and had the ability to run small armored boats across the coasts of China and Southeast Asia with little resistance. Escorts for landing parties could include support from destroyers and light cruisers at a distance, but closer support was just as important, especially since Japanese landing craft meant for transporting soldiers were usually not very well armed or armored.

Among a number of official and unofficial small craft used by Japan for river and coastal patrol, defense, and assault were the Japanese “AB Tei” armored gun boats (AB艇装甲艇). These armored craft used the same Type90 57mm tank gun as in the Type89 I-Go Medium Tank. They had 6mm of armor, which was enough to defend against small arms or distant machine gun fire. These boats were sometimes used to escort Daihatsu-class landing craft and were active along the coasts and on rivers during and prior to WW2. Having one or two of these craft slightly off shore supporting Japanese landings would be historically accurate for game scenarios.

Note the turrets and tank guns in the photo of the AB Tei armored boat below:

Transport Ships:

Perhaps most important to Japan’s amphibious assaults were large transport ships capable of delivering both men and armor. Among these were ships such as the IJN Transport No. 101 Class (seen in scale model form below) that bore amphibious assault tanks like the Type2 Ka-Mi, and traditional tanks like the Type95 Ha-Go. Much more common were ships that appeared more like typical gunboats or destroyers, like the IJN No. 1 Class Fast Transport ships.

These ships can be used in any scenario, though probably would be best in games as static “window dressing”. It is noteworthy that they could indeed fire upon enemies if approached, and in the case of the No. 1 Class Fast Transport were versatile warships in their own right.