Hi. It is a less known fact that the japanese army had a large naval branch, too. It consisted of special landing craft motherships, transport and supply vessels, landing craft in various sizes, armed landing support ships, speedboats and even escort aircraft carriers and transport submarines. IJA employed up to 300000 soldiers for naval duties and managed up to 30 % of the japanese merchant ships during the war. The first sino-japanese war 1894/95 showed that an island army like the japanese army depends heavily on shipping. This includes troops, material, supply and reinforcements. As the IJN was (at this time) small and mainly built for high sea duties it could provide only limited support. In the mid-twenties the decision was made to build up am army naval branch. As IJN had no infantry elements at this time one of the main purposes of the army naval branch had to be amphibious landings and supply of the landed forces. Due to the poor finances after the large earthquake in 1923 it took more than 10 years to develop and buy the needed landing craft and support ships. In 1935 the world´s first special purpose landing craft mothership Shinshu Maru was commissioned. It couild carry several landing craft and landing support craft. During the innitial stage of the 2. sino-japanese war 1937/38 Shinshu Maru played a major role by supporting several amphibious landings along the eastern chinese shores. Due to the raised funds IJA was able to lay down several more landing craft motherships in the late 1930th. Two of them were even designed to carry several aircraft which should be launched ashore to support the landing forces and to provide a minimal air cover. During the innitial stage of the Pacific War they support several landings in Malaya, Philippines, Netherlands East India (today Indonesia), Borneo, various pacific islands and Burma. As the tide of war changes in 1942 the japanese supply lines became more and more attacked by allied aircraft and submarines. The ship losses reached a dangerous level in 1943 and IJN wasn´t able to provide the necessary cover. So IJA decided to convert the landing craft motherships equipped with aircraft handling facilities to anti-sunbmarine escort carriers and to convert some merchant ships to escort aircraft carriers. Due to the lack of raw material the conversions took a lot of time and some were even not finished in August 1945. In 1944 the foreward supply lines were almost cut-off by allied submarinnes and aircraft. So IJA started to built small fast transport craft and unarmed transport submarines to provide at least minimal support for foreward island garrisons. In the following weeks I will add some short descriptions of the army crafts and vessels to this article. Yours tom!
It is interesting that they were prepared to allocate equipment and roles to whichever branch of the service seemed appropriate. Their armed forces were new enough not to let tradition get in the way. In many ways it is perfectly logical to have the army operate its lown landing craft, but in the Britain or the US, there would be a huge amount of vested interests and inter-service politics to get round first. Though to be fair, today's British Army does have a few of its own landing craft.
Hi. Let´s start with the landing craft: General: The japanese army started development of landing craft in 1924. All types should also be used by IJN and as the navy had the necessary technical backgrounds development was done in cooperation with IJN. The army needed two types of landing craft: 1. boats specialised on cargo/supply transport 2. boats specialised on equipment transport In 1927 a cargo craft became ready for production. It was named "Army SB-C type" or "Shohatsu" (Sho-Hatsudo-Tei = small engined boat): length: 10,6 m width: 2,44 m weight: 3,75 t loading capacity: 3 t or 30 soldiers engine: 1 X gasoline, later diesel with 60 hp maximum speed: 10 kts armament (IJN only): 1 X Type L 7,7 mm MG, later type 92 7,7 mm MG on the bow It had a steel motorboat-type hull with a freeboard of 1,2 m and a spiral screw, which was useful to avoid the obstacles in the water. It was a reliable vessel and good in mobility. Shohatsu was widely used in China and in the early Pacific War. Some 1000 were built until 1943 and mainly used by IJA (IJN only bought 20). In 1930 a larger landing craft became ready for production. It was named army LB-D type or "Daihatsu" (Dai-Hatsudo-Tei = large engined boat): length: 14,88 m width: 3,35 m weight: 9,5 t loading capacity: 12 t or 70 soldiers or 1 X type 89 medium tank or smaller engine: 1 X gasoline, later diesel with 60 hp maximum speed: 9 kts armament (IJN only): 2 X Type L 7,7 mm MG, later type 92 7,7 mm MG or 2-3 type 96 25 mm aa-guns Daihatsu has a steel hull and a spiral screw as well as Shohatsu. An armor plate was placed in the front of the pilot to provide cover against shots mainly from the front. A ramp was mounted at the bow to load and unload a vehicle or equipment. The bottom of the bow was W-shaped in order to stabilize the vessel when it lands on the beach. Some 6000 were built until 1945 with 3229 bought by IJN Daihatsu was the most successful landing vessel of the IJA and it was widely used for the landing opertation and transport. Some were even armed with an AT gun or AA machine cannon and used as gun boat. Yours tom!
Quite an interesting vessel. Simple idea but a couple of clever things like the spiral screw and W-shaped bow. Tom, do you know if any survived? I have this picture in my head of some Pacific island using one as their main mode of transport to the main island or something like that!
Hi. Looking at the total production number I´m sure that a lot of Daihatsu landing craft survived the war but I haven´t heard of one on display in a museum. Here is a nice japanese website with a lot of Daihatsu pictures loading and unloading vehicles and other equipment: click me By the way, here a picture of the standard japanese landing craft screw: Infantry landing: Yours tom!
Hi. With the introduction of the type 97 medium tank Chi-Ha in 1939 the Daihatsu landing craft was reworked to cope with the larger weight of the new tank (up to 16 t). In 1940 the new landing craft became ready for production. It was named "Army N-LB-D type " or "Toku Daihatsu" ("special Daihatsu"). length: 18,5 m width: 3,70 m weight: 17,5 t loading capacity: 16,5 t or 120 soldiers or 1 X type 97 medium tank Chi-Ha or smaller engine: 2 X diesel with 60-75 hp maximum speed: 10 kts The Toku-Daihatsu were larger and had two engines. Some 200 were built, the number bought by IJN is not clear In 1942 the number of landing craft had to be enlarged within short time to cope with the needs of an ocean war. So a wooden model of the Daihatsu was developed and intoduced. It was named "Mokusei Daihatsu" (short: Moku Daihatsu; "wooden Daihatsu"). length: 14,55 m width: 3,33 m weight: 11 t loading capacity: 10 t or 70 soldiers or 1 X type 89 medium tank or smaller engine: 1 X diesel with 60 hp maximum speed: 9 kts Various sorts of wood and plywood were used for production and several minor changes were made by local yards. About 1140 were bought by IJN, several thousand more by IJA, correct number not clear. Yours tom!
Hi. The Daihatsu landing craft were small and with limited payload.They had to be carried to the landing zones by landing craft motherships or transport vessels. They had to be loaded while laying besides the vessels making loading problematic even at quiet sea. And it took up to 17 hours to unload a vessel with 4000 t of supply using 2 cranes and several landing craft. This made supply during the early stages of an attack problematic. So the decision was made to built several larger landing crafts with a higher transport capacity. IJN designed a special craft with a bow door, small draught and reinforced hull using an ice breaker design. The first ships of this new class were laid down in late 1941 and launched in 1942. The design was named "Army SS.1 type" / "Navy ES type". length: 63,02 m width: 9,60 m displacement: 948 t draught: 3 m loading capacity: 630 t or 170 soldiers and 4 type 97 medium tanks Chi-Ha and 1 truck engine: 2 X diesel, 550 -600 hp each maximum speed: 13,5 kts armament (IJA): 1 X Type 88 75 mm aa-gun, 1 X type 98 20 mm aa-gun, 4 X type 97 150 mm mortar, 4 X type 92 7,7 mm MG The bow door had additional armour. Four type 97 150 mm mortars were mounted on the bow above the bow door for heavy close-range fire support. The machine guns were mobile. Mortars and machine guns could be transported ashore. Later during the war additionally several depth charges were loaded, too. 23 ships were built for IJA, few more for IJN. 4 more were laid down but destroyed or broken up before launch. 9 survived the war more or less damaged. Some were used for repatriation service and all were converted to small merchant vessels in 1946. Yours tom!
Good stuff, Tom. I always like seeing "obscure" (not widely talked about) gear surviving the war and being used - like the Army SS.1 type. I'd be surprised if any of those survived but I'm always surprised when I find out a Little Ship from Dunkirk or heavily modified MTB is found so there's always hope. Re the Daihatsu - the sign of a good design - easily modified for other uses!
Hi. In 1942 IJN decided to design an own LST with enlarged capacity especially for their amphibious tanks. The design included a bow ramp and the bow was fitted with a double skeg. In 1943 the first ships were laid down named "T101 type" with diesel egines and "T103 type" with Kampon boilers and turbines. In 1944 IJA decided to build several T103 type vessels designated "Army SB.101 type". length: 80,52 m width: 9,10 m displacement: 1025 t draught: 3,125 m loading capacity: 67,4 t and 120 soldiers or 14 light tanks and 218t or 9 medium tanks and 218 t engine: 2 X Kampon boilers, 1 X high pressure turbine and 1 X low pressure turbine on one shaft, 2500 hp maximum speed: 16 kts armament: 1 X type Taisho 3 8 cm aa-gun; 2 X tripple type 96 25 mm aa-gun, in 1945 additionally 3 X type 96 25 mm double-mount AA-guns and 4 X type 96 25 mm single-mount aa-guns late version 28 ships were laid down for IJA in 1944/45. 2 were sunk, 2 were broken up after surrender before launched, 6 were handed over to IJN in 1945, the rest surrendered and was used for repatriation services and broken up in 1947. No further infos, sorry. Here is a link to a photo album of somebody who built a 1:72 model of a T103 type: click me Yours tom!
Hi. During the innitial stages of an amphibious assault the landing craft are very vulnerable to enemy defence fire. So in 1924 IJA started the development of an armoured gunboat armed with machine guns and small infantry guns. In 1927 the first gunboats were delivered and named „Army-type armoured gunboat“ or „AB-Tei“ (not sure about the correct meaning, „Tei“ = boat): length: 17,10 m width: 3,50 m displacement: 30 t engine: 1 X gasoline, later 1 x diesel at 350 hp maximum speed: 13 kts armament: 1-2 X british 57 mm tank gun, later 1-2 X type 90 or type 97 57 mm tank gun; 1-2 X type Taisho 3 7,7 mm double-mount heavy machine gun, later type 92 double-mount 7,7 mm heavy machine gun At bow a turret with a gun was placed. The early gunboats had a second turret placed elevated behind the first turret with a MG or gun. A third turret with a gun or MG was placed on the superstructure at stern. Later the second turret was placed above an enlarged bridge. Due to weight limitations this turret was armed with MG only. These boats were transported to the landing zones aboard landing craft motherships or transport vessels. During the innitial stage of the landing they provide direct fire support for the landing forces. After a successful landing they were used to cover the operation at the flanks. A lot of gunboats were also used as river gunboats in the occupied countries The total production number is unknown A special thanks to Taki, who gives at least basic informations on these types of equipment on his website. Yours tom!
it is interesting to see,. on how those two branches of Japanese forces, Army and Navy, are totally self providing their own necessity without having to much depend on the other branch for assistance. However sadly for them, they also seems having each self goal in how and where to wage the war.
Hi. In 1922 JN bought a few british Thornycroft 55 ft coastal motor boats and tested them. After the tests IJA decided to build similar speedboats especially for scouting and communication purposes. The scout boat was named "Kosokutai Ko" (speedboat version A): length: 14,42 m width: 2,74 m displacement: 5,3 t engine: 1 X gasoline, 400 hp maximum speed: 37 kts armament: none Main purpose of this vehicle was high-speed reconnaissance just before the landings began to gather an actual view on surviving enemy equipment. Another pupose was fast transport of personell. Total production number is unknown. The smaller communication boat was named "Kosokutai Otsu" (speedboat model B) length: 11 m width: 2,43 m displacement: 4,5 t engine: 1 X diesel, 100 hp maximum speed: 13 kts armament: 1 X type 92 7,7 mm mg, 1 lmg These boats were not real speedboats due to the limited maximum speed. Main purpose was building up communication lines by serving as central communication platform on company level during the early stages on a landing. The boats were equipped with several wireless communication devices including optical (flags, morse lights, special optical communication devices). A hmg could be mounted above the bridge and a lmg was also aboard. Both speedboat types were introduced around 1930. A special thanks to Taki, who gives at least basic informations on these types of equipment on his website. Yours tom!
Hi. After the outbreak ot the 2. sino-japanese war 1937 IJA was able to exercise their amphibious landing tactics at war. The concepts were found successful but there were also improvements necessary. One problem was that neither IJA nor IJN was able to provide the necessary patrol capacities to secure habours and rivers. So IJA decides to develop patrol boats, too. There were several concepts based on IJN developments. All were armed with heavy automatic weapons or even tank guns. In 1942 one of these developments was officially introduced as type 2 patrol boat, armed with a type 98 20 mm aa-gun, later type 4 twin-mount 20 mm aa-gun at stern and a type 94 tank gun in a pivot mount in front of the bridge. Additionally a rack with two depth charges could ne mounted on each side at stern. Infos on these boats are rare, so no further infos, sorry Yours tom!
Hi. I was ill the last week so no new data last week, sorry. Some additions to Army SB.101 landing ships: Tanks, vehicles, soldiers and supply was transported in the transport deck between bridge and bow. Additionally tanks and equipment could be transported on the deck above the transport deck. After landing the bow ramp was lowered and vehicles and equipment were unloaded. After the transport deck was empty an internal ramp could be lowered to allow unloading the upper deck, too. The SB.101-class also carried a 9 m standard navy issue motorboat and a Shohatsu. In 1945 the naval T.101 and T.103-classes were fitted with a standard type 22 air and surface radar. I´m not sure if the army SB.101 were fitted with this radar, too. Yours tom!
This is a very interesting history, unfortunately I am unable to open the photos is there any way I can view them. Regards Alex.
Hi Alex, welcome aboard. I'm afraid some of the pics must have been linked on a photohosting site and Tom has since deleted them (which is why you see the little red crosses).
