Benten Daiba (弁天台場)As described below, during the period of the original daiba and the reconstruction planning, it was officially called "Benten Misaki Daiba" or "Benten Zaki Daiba," while "Benten Daiba" is a colloquial name that became widely used after the reconstruction. was a coastal battery constructed in the late Edo period in what is now Benten-chō (弁天町), Hakodate City, Hokkaido, as one of a group of coastal fortifications built to defend the northern territories of Ezo (modern Hokkaido) against the increasing presence of foreign ships. Initially a small-scale Japanese-style battery, in Bakumatsu (幕末), it was rebuilt as part of coastal defense enhancements following the opening of Hakodate Port to counter foreign vessels entering the port. Subsequently, it became a central component of Hakodate Bay's defenses and, during the Hakodate War (箱館戦争, Last phase of Boshin War at Oshima peninsula), served as a key defensive facility for the former-shogunate forces (旧幕府軍), engaging in fierce battles with the new government's naval fleet (see below). It is also known as Benten Misaki Daiba (弁天岬台場)," (嘉永三年)箱館ノ砲台弁天岬・山背泊・押付ノ三所ヲ修築ス" (in 1850, The Batteries at Hakodate, namely Benten misaki, Yamase-doma, and Otsuke, were repaired.) Hokumon Shiko (北門史綱) Volume 1; a record from the Matsumae Domain before shogunate rule, included in Matsumae Town History, Source Materials Volume 1 Benten Zaki Daiba (弁天崎台場)."Map of Hakodate Benten Zaki Battery (箱館弁天崎御台場図)" Hakodate City Central Library Digital Archives.The designation "Daiba (台場)" is sometimes replaced with the synonymous Japanese term "Hōdai (砲台)", as in the case of "Benten Daiba (弁天台場)" being written as "Benten Hōdai (弁天砲台)." The reconstruction was designed by Takeda Ayasaburō (武田 斐三郎)."其設計は、総て諸術調所教授武田斐三郎之を擔任せり。 (The design was entirely undertaken by Takeda Ayasaburō, a professor at the Shogunate's Institute of Various Arts.)" From the commentary on the history of Benten Daiba, included in Hokkaido History: Appendix Maps (北海道史 附録地図), 1918.
Structure and Military Strength of the Battery A large polygonal fortress shaped like an irregular hexagon, resembling a shōgi piece, with each side broadly facing various directions within the harbor, designed to encompass the entire surrounding sea within its firing angles.Plan of Benten Daiba, included in Hokkaido History: Appendix Maps (北海道史 附録地図), 1918. The total area was approximately 38,300 square meters. The enclosing fortifications featured an arched tunnel-style entrance at the southeastern end, with the lower part covered by a stone wall about 11.2 meters high, and consisted of an earthen rampart spanning about 780 meters around the perimeter.Hakodate Battery Construction Documents (函館砲台新築書類), Hakodate City Central Library Digital Archives.This fortification structure closely resembles the design used for outer rampart walls in European military theory from the 18th century through the 19th century, following the Cormontaigne System devised by the French fortification scholar Louis Cormontaigne. The image of Fort Romainville in France, which utilized the outer wall construction method of the Cormontaigne System, has been referenced and included.
The earth and stone were primarily quarried from Mount Hakodate (函館山), while critical components, such as the main gate, are said to have used Bizen Mikage granite transported from Osaka. The construction was overseen by Matsukawa Bennosuke (松川弁之助) for earthworks and Inoue Kisaburo (井上喜三郎) for masonry.Okada Kenzō (岡田健蔵) 1934 "Historical Sites and Scenic Spots.史蹟と名勝", Modern Hakodate (近代函館): Ryōjō Kengō Roku, History of Hakodate's Prosperity, Showa 9 Edition (稜城剣光録 函館繁栄史 昭和9年版), Kinseisha.
The battery was equipped with a total of 15 large fixed cannons, comprising two 60-pounder cannons and thirteen 24-pounder long cannons, with one cannon placed at each gun emplacement separated by the fortification walls.
Regarding these deployed cannons, there is a popular anecdote that in 1854, when the Russian ship Diana, carrying Putiatin for the Russo-Japanese Treaty of Amity negotiations, was wrecked and severely damaged by a tsunami caused by the Ansei Earthquake, the crew gifted 50 ship-mounted cannons to the shogunate as a gesture of gratitude to the residents of Shimoda who aided in the rescue. These cannons were purportedly used as part of Benten Daiba's armament.Ōtsuka Takatoshi (大塚高俊) 1934 "Modern Hakodate: Ryōjō Kengō Roku, History of Hakodate's Prosperity, Showa 9 Edition (近代函館: 稜城剣光録 函館繁栄史 昭和9年版)" Japan National Diet Library Digital Collection.Hakodate Nichinichi Shimbunsha (函館日日新聞社) 1935 "Hakodate City History (函館市誌)". National Diet Library Digital Collection.
A historical record believed to be related to this is found in the Kameda Goyakusho Goryōkaku/Benten Misaki Daiba Construction Records (亀田御役所五稜郭・弁天岬御臺場御普請御用留),Held by the Historiographical Institute, The University of Tokyo which states: "At this time, a total of 52 cannons were donated, and in 1860, the Hakodate Magistrate requested that 24 of them be allocated for Benten Daiba's armament, which was subsequently approved." In fact, while the budget and financial statements (see below) for Benten Daiba include detailed expenditures for cannon-related facilities such as gun carriages, rail-type fixed gun mounts, and gun platforms, there is no record of expenses for the purchase of the cannons themselves."Hakodate Chindai Historical Materials (箱館鎮台史料)" Vol.8 in "Edo (江戸)"5-2. Japan National Diet Library Digital Collection. This suggests the possibility that the deployed cannons may have indeed been sourced from those of the aforementioned ship.
In any case, both the "60-pounder cannon" (presumed to be the 60-pounder Parrott rifle) and the 24-pounder long cannon were large cannons with barrel weights alone reaching 2.5 tons. Unlike field artillery used in land battles against personnel, which were moved and towed by manpower or horsepower, these were designed as fixed-position anti-ship cannons targeting naval vessels, arranged around the entire perimeter. This equipment indicates that Benten Daiba was intended as a purely coastal defense battery.Coastal batteries, designed to counter naval artillery mounted in large numbers on ships capable of freely moving across the sea with propulsion, required anti-ship cannons with comparable firepower and range.
History of the Original Benten Daiba and Events Leading to Its Reconstruction Benten Daiba is located at the tip of Benten Misaki (弁天岬), a cape extending north from Mount Hakodate. Due to its position at the entrance of the crescent-shaped Hakodate Bay, a Japanese-style battery relying on traditional gunnery had been established for coastal defense since the era of Matsumae Domain rule.From "Hokumon Shiko (北門史綱)", Volume 1, in 1850, Daijima Gohei (代嶋剛平), a Matsumae Domain clansman based in Hakodate, proposed the reconstruction of three batteries, Benten Misaki Daiba (弁天岬台場), Yamase Domari daiba (山背泊台場), and Otsuke Daiba (押付台場), located on the western side of Mount Hakodate. Daijima later came under the command of the Hakodate Magistrate (箱館奉行) and was involved in the reconstruction of Benten Daiba, which began in 1856. However, as of October 1854, just before the shogunate's direct control, the personnel assigned to Benten Daiba consisted of only one samurai, two retainers, and six foot soldiers,"Regarding the Number of Personnel for Hakodate Defense (箱館警固人数の件)" from the lord of Matsumae domain the Hakodate Magistrate. Ancient Documents of Japan: Foreign Relations Documents of the Late Edo Period (大日本古文書 幕末外国関係文書), Volume 8, 19. making it merely one among many batteries and far from a significant force.In fact, Yamase Domari Daiba, which was later abandoned, had more personnel assigned than Benten Daiba at the time (Yamase Domari Daiba: 1 samurai, 3 retainers, 9 foot soldiers).
With the opening of Hakodate as a port in 1854 following Japan's opening to foreign trade, and the transfer of the surrounding area to shogunate control, the Hakodate Magistrate (箱館奉行), a distant administrative post, was reestablished. However, Hori Toshihiro (堀利煕), who arrived to assume this role, was concerned about several issues: the city of Hakodate, clinging to the foothills of Mount Hakodate, where ships anchored densely within the crescent-shaped bay, leaving no escape route in the event of conflict;"巴頭之如く一塊之孤山海上に突出致し、港湾を抱居候儀ニ付、四面海ニ対し、纔周海三里余の場所に有之、尤大洋江向ひ候方は険岸故、万一之儀有之候共用意ニ上陸等難致候得共、右孤山之麓ニ市廛稠密二櫛比致し、同所町外を桝形と申所より亀田村迄ニ沙地凡二十町程有之、横幅纔三百間計ニ而、東西海を帯し居候二付、軍艦一方に繋泊致し、炮門を開き候節は、通路難相成地勢に御座候 (Hakodate protrudes into the sea, isolated, with a unique topography surrounded by water on all sides, leaving no escape route if foreigners were to initiate conflict." Ancient Documents of Japan: Foreign Relations Documents of the Late Edo Period (大日本古文書 幕末外国関係文書), Volume 7, chap 248. the vulnerable coastal defense network composed of traditional Japanese-style batteries; the civilian homes and merchant shops in Hakodate's city center, intermingled with the Hakodate Magistrate's office; and the fact that foreigners, permitted to roam freely after the port's opening, could openly observe these defenses (sometimes even the magistrate's facilities from atop Mount Hakodate)."文化度御役宅御取建相成候節とはご時世も相替り、夷人共港中船路も熟し、殊に亜米利加国江は、遊歩之地をも御差許相成候二付、右山上二登り一望仕候得ば、眼下ノ市中は勿論、是迄之役宅幷支配向住居為仕候場所等儘く見おろし、更に障屛も無之、人居多少之虚実も明白ニ相顕れ、其上勝手向庭先迄巨細儘く被見透而は、威厳を貯へ不測を示し候場合無之、平常御取締ニも甚だ差障り (Today, particularly due to the treaty allowing foreigners to freely roam the city, they can closely observe not only the civilian homes but also the magistrate's residence from atop the mountain, with the layout and deployment of buildings fully exposed to their scrutiny.)" Ancient Documents of Japan: Foreign Relations Documents of the Late Edo Period (大日本古文書 幕末外国関係文書), Volume 7, chap 248.
Hori meticulously documented this situation and, in September of the same year, submitted a report to the shogunate to address Hakodate's critical circumstances. He argued that leaving the area in its current state—a place that could be "Ippō-Hunsai(一炮粉虀, reduced to dust with a single cannon shot)Ancient Documents of Japan: Foreign Relations Documents of the Late Edo Period (大日本古文書 幕末外国関係文書), Volume 7, chap 248."—would undermine morale, making it difficult not only for himself but also for subordinates to relocate there with their families."且先年之儀は支配向在勤ニ御座候共、今般は家内引纏在住仕候處、右様一炮粉虀之地ニ妻児家財共差置候而は、自然士気ニも相響可申哉と深く痛心仕候 (Under these circumstances, those assigned to this post are ordered to relocate with their entire families. Placing wives and families in such a perilous location, where a single cannon shot could reduce everything to dust (ippō funsai), would greatly affect the morale of the personnel, causing me deep concern.)" Ancient Documents of Japan: Foreign Relations Documents of the Late Edo Period (大日本古文書 幕末外国関係文書), Volume 7, chap 248. As a solution, he requested the construction of a magistrate's office in Kameda (亀田) or Arikawa (有川, near present-day Hokuto City) on the opposite shore, concealed from external view and with a secure escape route."右ニ付、何れニも御役宅幷支配向住居之場所等は、松前続キ山巒を後ニ取、海湾を前に当る亀田、有川辺ニ而、水路の便を求め、樹陰見隠れ等も可然地所夫々相撰御引移罷成、足手纏ひのもの共為立退候後路も備置、身後之懸念無之様、平常共用意行届候様仕置度 (For the above reasons, the location for the magistrate's office and the administrative residences and workplaces should be set in Kameda (亀田) or Arikawa (有川), with the long mountain range from Matsumae at the back and the sea in front. Consideration should be given to the convenience of concealment through water transport or forests, while also securing an escape route for families.)" Ancient Documents of Japan: Foreign Relations Documents of the Late Edo Period (大日本古文書 幕末外国関係文書), Volume 7, chap 248.