Siege of Nirengi Castle
Date: Genki 2 (1571)
Location: Nirengi Castle in the Atsumi District of Mikawa Province
Synopsis: In the second month of 1571, Takeda Shingen invaded Tōtōmi Province but withdrew after facing stiff resistance at Takatenjin Castle. In the fourth month he then launched an invasion of eastern Mikawa. Rather than assault the stronghold of Yoshida Castle, he directed his forces to capture ancillary castles including Nirengi Castle. After Tokugawa Ieyasu consolidated troops at Yoshida Castle, Shingen determined he could not afford a protracted siege so he withdrew his forces to Kai.
The Siege of Nirengi Castle occurred in Genki 2 (1571). Nirengi Castle was situated on the southern shore of the Asakura River on the northern end of the Atsumi District of Mikawa Province. Nirengi Castle was an ancillary base to Yoshida Castle, a stronghold of the Tokugawa in eastern Mikawa. The conflict was waged between the armies of Takeda Shingen and Tokugawa Ieyasu during an invasion by Shingen of Mikawa.
After subjugating Suruga Province by 1570, Takeda Shingen invaded Tōtōmi Province. From the time of the Invasion of Suruga in 1568, Shingen aimed to expand his territory to Tōtōmi and had forces led by his retainer, Akiyama Torashige (Nobutomo), invade Tōtōmi. Meanwhile, Tokugawa Ieyasu moved his residence to Hamamatsu Castle in Tōtōmi, making clear his opposition to the Takeda.
In the second month of 1571, Shingen led 25,000 soldiers, traversed the Ōi River, and invaded the territory of the Tokugawa in Tōtōmi. On 3/5, the army assaulted Takatenjin Castle in eastern Tōtōmi. Strategically located and situated in steep terrain, the castle proved difficult to capture so Shingen decided to halt the offensive and temporarily withdraw north to Shinano Province.
After regrouping, Shingen led his forces south on the Iida Road to invade eastern Mikawa. In response, Ieyasu amassed his forces in Tōtōmi to prepare for an invasion by the Takeda army so the Tokugawa misread the situation. Suzuki Shigenao was the commander in charge of Asuke Castle situated in a vital location on the provincial border of Shinano and Mikawa on the Iida Road. Fearing the approach of the Takeda army, he fled to Okazaki Castle so, on 4/22, Asuke Castle fell to the Takeda. After toppling Damine Castle defended by Suganuma Sadatada, the Takeda marched south with Sadatada serving as their guide. On 4/28, the army assaulted Noda Castle defended by Suganuma Sadamitsu, capturing the castle on 4/29.
Next, Shingen attacked Yoshida Castle in eastern Mikawa. Yoshida Castle was a stronghold built on a hill at the convergence of the Toyo and Asakura rivers commanded by Sakai Tadatsugu, a leader in eastern Mikawa for the Tokugawa family, making its capture difficult for the Takeda. Shingen then changed his objective to target ancillary castles of Yoshida Castle and launched an assault on Nirengi Castle defended by the Toda clan, located two kilometers to the east of Yoshida Castle.
Meanwhile, Ieyasu led 5,000 soldiers to serve as a rear guard for Nirengi Castle but was defeated and withdrew to Yoshida Castle. As a result, Nirengi Castle was toppled but the armies led by Ieyasu and Tadatsugu holed-up in Yoshida Castle so an effort by the Takeda to topple it would necessarily entail a lot of time and losses of troops. For the Takeda, a prolonged battle raised the risk that Ieyasu’s ally, Oda Nobunaga, would come to reinforce the defenders, moreover, Hōjō Ujimasa could use it as an opportunity to invade Suruga Province. Therefore, Shingen canceled an assault on Yoshida Castle and withdrew his forces to Kai.