This category contains all ships classified as Coastal Defense Ships.

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In Kancolle, "Coastal Defense Ships" are labelled as "DE", whereas in real life, DE designates "Destroyer Escort".

Historical background

Developed originally as fishery protection ships, with a secondary minesweeping and tertiary convoy escort wartime function, the Shimushu class coastal defence ships (Kaibōkan) became during the war the template for the main type of oceanic convoy escorts built by the IJN. These ships were initially conceived in the early 1930s, a resurgent Russian naval presence in the Far East resulted in a number of incidents involving Japanese fisheries in disputed waters, they were consistent with the unlimited category (Article 8) of the London Naval Treaty of 1930 that allowed to build ships like the British sloops, French avisos and the American Erie class patrol gunboats, but they were effectively authorised and built only with the 1937 naval programme, after Japan had left the Treaty system and the Second London Naval Treaty had removed those quantitative limitations that justified the introduction of an unlimited category.

Originally coastal defence ship was a classification used for obsolete battleships and cruisers deemed unfit for first-line duties and assigned to coastal defence, it became a separate classification that included only the new escorts in July 1942, the surviving obsolete armoured cruisers were reclassified as heavy cruisers; the new classification was also moved from the Gunkan sub-group, which included main combatants like battleships, cruisers, carriers, etc. to the baseline Kantei group, which included destroyers, submarines, torpedo boats, etc.

The lack of an ASW emphasis in the Shimushu class can be evidenced from the limited depth charge stowage (12, increased to 24 since May 1942 and 60 since Autumn 1943) and the lack of sonar until Autumn 1942, coastal defence ships became genuine, purpose-built, convoy escorts only with the Mikura class, that was fitted with sonar since the beginning and carried 120 depth charges, albeit the minesweeping gear was dropped from the plans only with the Ukuru class. Mass production wasn't attempted until the Ukuru class and the Type C&D, which extensively employed welding and pre-fabrication.

During WWII the coastal defence ship classification was also used for the two former Chinese light cruisers Ning Hai and Ping Hai, in late 1943 the IJN decided to rebuild the two idle ships into escorts with a radically altered superstructure and armament analogous to the Type C&D kaibokan, they were respectively renamed Iaoshima and Isoshima. These relatively large ships were also supposed to serve as tenders for aircraft bases, for this purpose they were equipped with a crane on the mainmast, trucks, one daihatsu (14-m) and one shohatsu (10-m) landing craft. Yasoshima was re-rated as a light cruiser for administrative reasons on 25 September 1944, it had been decided to appoint her as flagship for the newly organised First Transport Squadron, a role that required her to be rated as a light cruiser.