The or AB-tei class was a type of armored

gunboat A gunboat is a naval watercraft designed for the express purpose of carrying one or more guns to bombard coastal targets, as opposed to those military craft designed for naval warfare, or for ferrying troops or supplies. History Pre-steam ...

used by the

Imperial Japanese Army The was the official ground-based armed force of the Empire of Japan from 1868 to 1945. It was controlled by the Imperial Japanese Army General Staff Office and the Ministry of the Army, both of which were nominally subordinate to the Emperor o ...

from 1928 to 1945 in the

Second Sino-Japanese War The Second Sino-Japanese War (1937–1945) or War of Resistance (Chinese term) was a military conflict that was primarily waged between the Republic of China and the Empire of Japan. The war made up the Chinese theater of the wider Pacific Th ...

and

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

. It was constructed of a metal hull and powered by a

diesel engine The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-call ...

. It was designated the "Type C" landing craft by the United States.

History

During the 1920s, the

developed equipment for a complete suite of capabilities during amphibious assaults. They developed the ''Shohatsu'' and the ''Daihatsu'' classes of landing craft; a ship-to-shore communications boat, the ''HB-O'' ( :ja:高速艇乙); a reconnaissance gunboat, the ''HB-K'' ( :ja:高速艇甲); and the world's first

landing craft carrier Landing craft carriers or landing craft depot ships were an innovative type of amphibious warfare ship developed by the Imperial Japanese Army during World War II. The prototype was developed in secrecy under the pseudonyms ''Ryujo Maru'' and ''Fus ...

( ''Shinshū Maru''). The armored boat was developed to provide close-in support for amphibious operations and was transported the same as the other landing craft. The prototype boat was completed in 1928 (Showa 3) and named ''Sakigake'' (さきがけ or "Pioneer" in Japanese). It was 14.4 meters, displaced 16 tons, ran on gasoline, and was armed with two 6.5 mm ''Type 38'' machine guns ( :jp:三八式機関銃) and one 37 mm "''Sniper''" gun ( :jp:狙撃砲). In 1930 (Showa 5), the second boat, ''Kachidoki'' (勝鬨 or "Battle Cry" in Japanese), was completed. It was larger at 20 meters and 20 tons of displacement, ran on diesel fuel, and its armament was upgraded to one 57 mm ''Type 90'' tank gun ( :jp:九〇式五糎七戦車砲) and two 7.7 mm ''Type 89'' swivel guns ( :jp:八九式旋回機関銃). In 1932, ''Kachidoki'' saw action during the landing operation at

Shanghai Shanghai (; , , Standard Mandarin pronunciation: ) is one of the four direct-administered municipalities of the People's Republic of China (PRC). The city is located on the southern estuary of the Yangtze River, with the Huangpu River flow ...

during the January 28 incident. The third boat was reduced in size to 15.5 meters with 17.5 tons displacement while keeping the same armament as ''Kachidoki''. ''Armored Boat No. 3 (AB-3)'' was chosen as the final design and in 1933, 23 additional boats were built (designated ''AB-4'' through ''AB-26''). In 1937, the design was again changed increasing the length to with 20 tons displacement and the speed increased to ; ten boats of this configuration were built. In 1938, the design was reduced in length to with 20 tons displacement and a second 57 mm tank gun added; 11 boats of this configuration were built by

Osaka Iron Works is a major Japanese industrial and engineering corporation. It produces waste treatment plants, industrial plants, precision machinery, industrial machinery, steel mill process equipment, steel structures, Heavy equipment (construction), construc ...

(大阪鉄工所, Ōsaka Tekkosho). In 1939, the displacement of the ship was reduced to 16.5 tons and the second 57 mm tank gun removed; 19 boats of this configuration were built by Osaka Iron Works. After the

Battle of the Bismarck Sea The Battle of the Bismarck Sea (2–4 March 1943) took place in the South West Pacific Area (SWPA) during World War II when aircraft of the U.S. Fifth Air Force and the Royal Australian Air Force (RAAF) attacked a Japanese convoy carrying troops ...

(2–4 March 1943) where eight transports and four destroyers were lost to enemy air attacks, the Japanese relied on convoys of barges escorted by armored boats to replenish or evacuate their forces. A typical configuration allowing for the transport of 1,000 men, 300 miles, would consist of 2 armored boats as escort for 2 special large landing barges ( ''Toku Daihatsu''), 40 large landing barges ( ''Daihatsu''), and 15 small landing barges ( ''Shohatsu''). Due to her slow speed, she was eventually outclassed by the American

patrol torpedo boat A PT boat (short for patrol torpedo boat) was a motor torpedo boat used by the United States Navy in World War II. It was small, fast, and inexpensive to build, valued for its maneuverability and speed but hampered at the beginning of the wa ...

and a Japanese equivalent was developed ( :ja:カロ艇). She is not to be confused with the ''ST-class'' armored boats built by Mitsubishi Heavy Industries Ltd. at their Yokohama Shipyard for riverine patrol in China.

References

*Masao Fujita ''Unknown Records of Army Ship Corps'', April 2008 issue, Tide Shobo {{WWII Japanese ships Ships of the Imperial Japanese Army Amphibious warfare vessels of Japan Ships built by Osaka Iron Works