Yoshinari MORI, the lord of Usayama-jo Castle, attempted to intercept the advance of the allied forces by preemptively conquering Sakamoto (Otsu City), a strategic point of transportation, to help blockade roads along with Nobuharu ODA, the lord of Nobu-jo Castle, and Shigetsuna AOCHI.
城主・森可成は近江に居た野府城主・織田信治、青地茂綱らと共に交通の要所である坂本(大津市)を先に占領して街道を封鎖して連合軍の進軍妨害を試みる。