It is thought that Mitsunari, contemplating what to do if the worst occurred and his side was defeated in the battle of Sekigahara, planned to regroup at Sawayama-jo Castle and continue the war from there.
三成は関ヶ原の戦いに万が一敗北した場合を考え、佐和山城で再戦を意図していたとされる。