HTMS Thonburi was a Siamese coastal defense ship, sometimes classified as a coastal defense battleship, from the interwar period and World War II The keel for this unit was laid in 1936, the launch took place in July 1937, and the entry into service took place in January 1938. The total length of the ship at the time of launching was 77 m, with a width of 14.4 m and a draft of about 4.2 meters. The displacement was about 2,270 tons and the maximum speed was about 15.5 knots. The armament at the time of the launch consisted of, among other things, four 203 mm guns, four 76 mm universal guns and 4 20 mm anti-aircraft guns.
HTMS Thonburi, along with its sister unit HTMS Sri Ayudhya, were commissioned by the Siam Navy and were built by the Japanese Kawasaki plants. During the design and construction of both these units, the experience gained from the operation of the Ratanakosindra class units was clearly based. First of all, the new ships, compared to their predecessors, have a much stronger main armament (203 mm guns instead of 152 mm), and the units themselves have been significantly enlarged and better armored. Incidentally, it can be added that the main artillery HTMS Thonburi and The HTMS Sri Ayudhya was the same as the Japanese heavy cruisers (e.g. the Mogami class). Both units were rated highly useful in the Siamese fleet. However, the combat trail HTMS Thonburi was relatively short, as he had to fight one more serious naval battle during World War II - the Battle of Koh Chang in January 1941 - which, moreover, ended in a disgraceful defeat for the Siamese side.