Fuji River
In 1600, Masanori sided with Tokugawa Ieyasu 'Eastern army' at the Battle of Sekigahara. He was the leader of the Tokugawa advance guard. He started the battle, and charged north from the Eastern Army's left flank along the Fuji River attacking the Western Army's right centre. Masanori troops fought against Ukita Hideie army, what is said to have been one of the bloodiest confrontations in the battle. Ukita's troops were winning the battle, pushing back Masanori's army. However, after Kobayakawa Hideaki changes side to support Eastern army and his action forced the other armies to had pledged a betrayal. Later, Masanori's army was winning the fight and the Eastern Army won the battle.