Egawa Tarozaemon Hidetatsu (1801-55) who was ”Daikan” (the local governer) of Nirayama (Nirayama of Shizuoka Prefecture), was ordered by the Edo Shogunate to visit and study the Edo Bay in Tenpo 9 (1838). In Tenpo 10 (1839), Egawa submitted a report to the shogunate. In which, Egawa considered the line connecting Kannonzaki and Futtsu Cape was the most important defense line and proposed to construct Daiba batteries at Kannonzaki and Hashirimizu and a Daiba in the sea off Futtsu Cape to protect this line. The scholar of Western studies Kazan Watanabe (1793~1841) asked by Egawa edited the Edowan Kaibo Keikaku (Tokyo Bay Sea Defense Plan) in the same year. In this plan, proposals for the underwater Daiba at Futtsu Cape and Shinagawa Daiba were written already.
Egawa Tarozaemon Hidetatsu
Kazan Watanabe :”Edowan Kaibo Keikaku” (Tokyo Bay Sea Defense Plan)
Tenpo10（1839）
[Data]Shosuke Sato：”Kazan Watanabe ‘Shokoku Kenchisozu'”
