text: In 1561, It was said that when he just reached 14 old age, Tadakatsu recorded his first kill in battle. At first his uncle, Honda Tadazane, killed an enemy samurai and asked Tadakatsu to cut off the corpse head as trophy for Tadakatsu. However, Tadakatsu stated that he did not want to rely on others to achieve military merit. Tadakatsu followed suit by charging towards the enemy rank and made his own trophy by killing an enemy by his own hand.
  Tadakatsu, who became the head of the core branch of Honda clan, was at first a follower of Jōdo Shinshū (True pure land Buddhism). However, as radical sectarian rebels of Ikkō-ikki which following Jōdo Shinshū broke out, Tadakatsu abandoned Jōdo Shinshū and changing his faith to Jōdo-shū(pure land Buddhism), as he stay loyal to Ieyasu. Tadakatsu joined Ina Tadatsugu, Sakai Tadatsugu, Mizuno Sanzaemon, Torii Mototada, Ōkubo Tadakatsu, and Ishikawa Tadanari to support Ieyasu in suppression of Ikkō-ikki.
  Around 1561-1563, The Ietada nikki journal has stated at some point of this rebellion, 200 Tokugawa soldiers led by Tadakatsu and Ishikawa Ienari were ambushed and routed by Ikkō-ikki rebels led by Sakai Tadanao.
  In June 1564, Tadakatsu competes with Hachiya Sadatsugu to be appointed as vanguard commander to attack Yoshida Castle. In the end, Tadakatsu were chosen to lead the troops and they manage to defeat the garrison and forcing the castle to surrender. However, Sadatsugu were killed during the battle by the enemy commander Masanori Kawai. In 1566 , at the age of 19, Tadakatsu was promoted Hatamoto and was given command of 54 cavalry soldiers.