Siege of Futamata Castle
Year: 10/16 to 12/19 of Genki 3 (1572)
Location: Futamata Castle in northern Tōtōmi Province
Outcome: Nakane Masateru and a garrison of 1,200 men attempted to defend Futamata Castle against a siege by the Takeda army, but later surrendered after the Takeda cut their water supply.
The Siege of Futamata Castle occurred from 10/16 to 12/19 of Genki 3 (1572) in the northern part of Tōtōmi Province. The conflict was waged between Takaeda Shingen and Tokugawa Ieyasu in the course of events comprising Shingen’s Western Campaign.
On 10/3 of Genki 3 (1572), Takeda Shingen, the sengoku daimyō of Kai Province with aspirations to march upon the capital of Kyōto, invaded the territory of Tokugawa Ieyasu in Tōtōmi Province.
To separate the outlying castles of the Tokugawa in Tōtōmi from east to west, on 10/13, he assigned a division of soldiers to his trusted commander, Baba Nobuharu, to capture Tadarai Castle. Meanwhile, Shingen himself led 22,000 soldiers and, in a single day, toppled Amagata, Ichinomiya, Iida, Kakuwa, and Mukasa castles. On 10/15, the army attacked Sagisaka Castle. This resulted in the isolation of Kakegawa and Takatenjin castles while the Tokugawa were forced to fight against the Takeda with only the forces based in Hamamatsu Castle. Therefore, on 10/14, at the Battle of Hitokotozaka, Ieyasu suffered a bitter defeat to Shingen.
After achieving this series of victories over Ieyasu, on 10/16, the Takeda forces proceeded to surround Futamata Castle. Futamata was located just mid-way between Kakegawa and Takatenjin castles and, relative to the position of other castles in Tōtōmi, in a particularly critical location. The capture of Futumata would enable the Takeda to secure their supply routes as well as to sever the communications network of the Tokugawa army.
Course of events
Futamata Castle stood atop a hill at the convergence of the Tenryū and Futamata rivers. This was an impregnable castle protected by the rivers which served as natural moats. Nakanae Masateru served as the chamberlain and Aoki Sadaharu served as the vice-chamberlain of the castle, overseeing a garrison of 1,200 soldiers. Meanwhile, with the addition of the forces under Baba Nobuharu, Shingen’s army totaled 27,000 forces giving them the option of attempting to topple the castle by force.
Expecting the arrival of reinforcements from Ieyasu or their ally, Oda Nobunaga, Masateru refused solicitations from Shingen to surrender. As a result, beginning on 10/18, the Takeda army commenced offensive operations. However, the only means to attack the castle was via the main entrance on the northeast side. Moreover, this main entrance was on a steep incline, impeding the progress of the Takeda forces so that, ultimately, they aborted the effort.
Yamagata Masakage, one of Shingen’s senior commanders, had earlier led a separate division to invade the Tokugawa territory in Mikawa Province. In the eleventh month, upon orders of Shingen, Masakage converged with the forces led by Shingen. However, the offensive by the Takeda army stalled as the battle continued into the twelfth month.
Shingen determined that it would not be possible to topple Futamata Castle by force, so he turned to the tactic of severing their water supply. Futumata did not have its own well. Instead, water was brought up by dropping a well bucket from a watch tower on a cliff along the Tenryū River. Shingen then adopted a plan by which his forces would construct a large number of rafts to float down from upstream on the Tenryū River to collide with and break the pillars supporting the tower. This plan succeeded, with the rafts smashing into the pillars and toppling the watch tower so the defenders could no longer draw water from the river below.
After eliminating their access to water, Shingen pressed ahead to force open the castle. In case of an emergency, Masateru had stored rainwater in tubs, but with 1,2000 defenders on site, the stored water would not last for long. Therefore, he decided to surrender and vacate the castle, fleeing to Hamamatsu Castle.
The attack on Futamata Castle was a decisive event in determining the relative strength of the Takeda vis-à-vis the Tokugawa. As a result, almost all of the clans who were resigned to wait and see the outcome, including provincial samurai from the Iinō, the Kamio, the Okuyama, the Amano, and the Nukina clans, pledged their allegiance to the Takeda.
Consequently, Ieyasu’s base at Hamamatsu Castle became the next objective for Shingen, which, on 12/22 of Genki 3 (1572), led to the Battle of Mikatagahara.