It was also because Tadateru put to the sword two hatamoto (direct retainers of the bakufu, which is a form of Japanese feudal government headed by a shogun) under Hidetada because they overtook Tadateru's force in Mt. Mori in Omi Province which was marching toward Osaka (However, under military law at that time, Tadateru's actions were legal as during the war kirisute gomen [cut, apologize, and walk away]) was allowed in the case of overtaking.
忠輝軍が大坂に向けて進軍中、近江国守山で軍列を追い越したとして、秀忠直属の旗本2名を斬り殺したため（但し、当時の軍法では戦中の追い越しつまり乗り打ちは切り捨て御免となっているので忠輝の処置は合法である）。