Battle of Hitokotozaka
Date: 10/13 of Genki 3 (1572)
Location: At Hitokotozaka in Tōtōmi Province
Outcome: A reconnaissance unit from the Tokugawa encountered a vanguard division from the Takeda who gained the upper hand and forced the Tokugawa forces to flee.
The Battle of Hitokotozaka occurred on 10/13 of Genki 3 (1572) waged between Takeda Shingen and Tokugawa Ieyasu. The battle occurred at Hitokotozaka in Tōtōmi Province in the course of the Western Campaign of Takeda Shingen as a preliminary clash to the Siege of Futumata Castle and subsequent Battle of Mikatagahara.
In 1572, Takeda Shingen acted in concert with the Encirclement Campaign against Nobunaga by launching the Western Campaign. Shingen divided his army into three divisions, with Yamagata Masakage leading 5,000 soldiers to Mikawa and Akiyama Torashige leading advance units comprised of the Ina group (forces from Shinano) to Mino. On 10/10, Shingen himself led a division of 30,000 soldiers (including reinforcements provided by Hōjō Ujimasa) and marched from the Aokuzure Pass in Shinano to attack the Tokugawa territory in Tōtōmi.
After the start of the invasion by the main division, a kokujin, or provincial landowner, named Amano Kagetsura in northern Tōtōmi suddenly switched his allegiance to Shingen, vacated his base at Inui Castle, and served as a guide for the invasion of Tōtōmi. At Inui Castle, Shingen allocated 5,000 soldiers to Baba Nobuharu and sent them toward Tadarai Castle to the west while he continued to march south toward the strategic position of Futamata Castle. Meanwhile, the Yamagata forces, in addition to the Yamaga-Sanpō group from Oku-Mikawa that had already surrendered, turned toward Tōtōmi with the intention of converging with the main division led by Shingen.
Futamata Castle was in a strategic location (like the pivot of a fan) not only for the main base of the Tokugawa clan at Hamamatsu Castle, but also for the outlying castles of Kakegawa and Takatenjin in Tōtōmi. For the Tokugawa, it was essential to the governance of Tōtōmi. Ieyasu, however, had to respond to Mikawa, and could only mobilize 8,000 men for its defense. Moreover, he could not count on reinforcements from the Oda clan. And, despite not wanting to have them cross the Tenryū River, he sent Honda Tadakatsu and Naitō Nobunari on a reconnaissance mission, while Ieyasu himself led 3,000 forces and crossed the river.
At this time, however, the Takeda army advanced more quickly than expected by Ieyasu.
Course of events
The reconnaissance unit led by the Honda and Naitō forces had a chance encounter with an advance party from the Takeda. The reconnaissance unit quickly withdrew, but, through nimble action, the Takeda forces initiated a pursuit of the Tokugawa army where clashes began along the Mikano River (a tributary of the Ōta River) and at Hitokotozaka.
The contest did not open in a way desired by the Tokugawa and, the Tokugawa were outnumbered, so Ieyasu decided to retreat. To enable the main division of the Tokugawa and the Naitō forces to escape, Honda Tadakatsu and Ōkubo Tadasuke served as the rear guard, standing guard in an unfavorable location below Hitokotozaka. The battle progressed at a rapid pace, with Baba Nobuharu leading a vanguard unit of the Takeda army to attack a vulnerable formation of Honda forces, breaking through the first two lines of a three-line defense. Meanwhile, Kosugi Sakon, an attendant of Shingen, led a unit around behind (from below Hitokotozaka) in an attempt to block the path of retreat of the Honda forces and fired arquebuses.
In response, Tadakatsu ordered a formation for an all-out attack with the aim of overwhelming the Kosugi forces positioned below them to enable their escape. This was a reckless offensive by the Honda forces, but Sakon ordered his soldiers not to intercept them and to the path of retreat, allowing the Honda unit to escape. At this time, Tadakatsu was said to have given thanks in the name of Sakon.
In this way, owing to the efforts of Honda Tadakatsu serving as the rear guard, the main division led by Ieyasu succeeded in crossing the Tenryū River and completed the withdrawal.
Although the Tokugawa army safely withdrew to Hamamatsu Castle, as of 10/16 of Genki 3 (1572), the Takeda army continued to surround Futamata Castle. Ieyasu could not respond to this situation, and, on 12/19, in an event known as the Siege of Futamata Castle, the castle fell to the Takeda forces. This shook the governance of Ieyasu in Tōtōmi.
Around the time of the fall of Futamata Castle, Ieyasu received additional forces from the Oda clan. After its fall, Ieyasu determined that Hamamatsu Castle would be the next target for the Takeda. While planning for a siege of the castle, the Tokugawa were drawn out into a field battle and overwhelmingly defeated at the Battle of Mikatagahara.