Saitō Dōsan
In 1556, Nobunaga destroyed a rival branch of the Oda clan located in Kiyosu Castle. At the same time, Nobunaga sent an army to Mino Province to aid his father-in-law, Saitō Dōsan, after Dōsan's son, Saitō Yoshitatsu, turned against him. The campaign failed, as Dōsan was killed in the Battle of Nagara-gawa, and Yoshitatsu became the new master of Mino.