text: Campaign against Takeda clan In 1572, during the Takeda clan campaign in Mikawa, Tadakatsu participated in the forces of Tokugawa. Ieyasu sent him, Naitō Nobunari, and Ōkubo Tadasuke, to lead the vanguard, where they meet Takeda forces led by Yamagata Masakage and Baba Nobuharu at the battle of Hitokotosaka. It is said that in this battle Tadakatsu gained recognition from the enemy forces for his antler helmet and his Tonbo-giri spear for his exploit in staving off the charges of Baba Nobuharu’s units. In the end of this battle, Tadakatsu and Naitō Nobunari fought well, as both of them managed to break through from the encirclement attempts by Takeda forces and managed to lead the Tokugawa forces to escape safely.
  In 1573, Tadakatsu also served at Tokugawa's greatest defeat, the Battle of Mikatagahara, where he commanded the left wing of his master's army, facing off against troops under one of the Takeda clan's more notable generals, Naitō Masatoyo. In the prelude of Tadakatsu manage to ward off the first wave, however, the Tokugawa forces getting overrun by the next waves of Takeda forces. In the last phase of the battle, Tadakatsu reportedly fought alongside Sakakibara Yasumasa engaging Takeda clan general named Oyamada Masayuki, while Ishikawa Kazumasa were busy covering the retreat of Ieyasu from the battle. In the end, the Tokugawa forces manage to withdraw safely from the battle due to dexterous performance of Tadakatsu in organizing the cover of their retreat.
  Later in the same year, Tadakatsu and Sakakibara Yasumasa were tasked to capture Nagashino Castle. Both of them manage to defeat the Takeda clan armies which guarded the castle and completed their mission to capture it. Aside from that, Tadakatsu also captured many other castles in Tōtōmi Province from Takeda clan.