text: Later, Honda Tadakatsu participated at the Battle of Sekigahara as one of Eastern army commander. At some point during this battle, Tadakatsu rode his horse, "Migoku-Kuro", to penetrate the ranks of the camps of Shimazu Yoshihiro and Ukita Hideie, two of Western Army commanders. However, Tadakatsu's beloved horse Migoku-Kuro was shot (or, according to one theory, hit by an arrow) during this moment, forcing Tadakatsu to desperately fought in the middle of by enemy soldiers encirclement, until his senior vassal, Katsutada Kaji, immediately came to his rescue and offered his horse to Tadakatsu from being surrounded by the enemies. Ōta Gyūichi chronicles of Daifu-Kō gunki has recorded, after several western army generals such as Ōtani Yoshitsugu and Shima Sakon along with his son were slain in the battle, Tadakatsu units surging forward against the western army unimpeded until reached Nakasuji, causing the western army to rout and flee down to the Tamafuji River.
  After the victory of Ieyasu forces in Sekigahara, Ieyasu rewarded Tadakatsu with domain increase of 150,000 koku. However, Tadakatsu refused this promotion, so Ieyasu instead assigned reward of 50,000 to Tadakatsu's son instead. Tadakatsu and Ii Naomasa engaged in peace agreement with Mōri Terumoto. Itazaka Bokusai (1578－1655), personal physician of Tokugawa Ieyasu, has recorded a memorial from anonymous soldier from Sekigahara in his work, "Keichō Chronicle", that after Ishida Mitsunari was caught and brought in to be executed, Tadakatsu came close while bowed politely towards Mitsunari, and saying "Lord Mitsunari has made a mistake".