The Type 4 15cm self-propelled gun Ho-Ro (日本語: 四式十五糎自走砲 ホロ, Imperial Japanese Army Type 4 15cm self-propelled gun Ho-Ro) was based on an already existing reinforced Type 97 Chi-Ha medium tank chassis developed by the Imperial Japanese Army in World War II.
The chassis selected was a modified Type 97 Chi-Ha medium tank chassis.[3] On to this platform, a Type 38 150 mm howitzer[3] based on a design by the German arms-manufacturer Krupp was mounted, but dated from 1905 and had been withdrawn from service as being obsolete in 1942.[4] The main gun could fire Type 88 APHE rounds and HEAT rounds, if necessary. Given its breech loader, the maximum rate of fire was only 5 rounds per minute.[5] The gun's elevation was restricted to 30 degrees by the construction of the chassis. The restricted elevation meant it was capable of firing a 35 kilogram shell 6,000 meters (6,600 yards). Other design issues included the fact that although the gun crew was protected by a gun shield with armor thickness of 25 mm at the front, the shield with armor thickness of 12 mm only extended a very short distance on the sides; leaving the rest of the sides and back exposed. In addition, the Ho-Ro did not have any secondary armament, such as a machine-gun, making it vulnerable to close combat.[6]
