Since Meiji 13 (1880), Imperial Army launched full-scale construction of fortress and planned initially to deploy own domes- tic artillery guns as much as possible, but they depended on foreign made cannons as it was quite difficult to produce all domesti- cally early on due to the poor production facilities and immaturity of domestic tech- nology.

After World WarIthe performance of war- ship had drastically improved and then older model of guns became obsolete and worthless. In this way The Tokyo Bay For- tress was forced to change its plan and construction to cope with the change of strategy and advancing technology through the transition of times of Meiji, Taisho and Showa.