In 1615, Sadatsugu was ordered by the Shogunate to commit suicide together with his son Juntei TSUTSUI on charge of his secret communication with the people of Osaka-jo Castle (the enemy) during Winter Siege of Osaka.
そして1615年、定次は大坂冬の陣で城方に内通したという責めによって、幕命により息子の筒井順定とともに自害を命じられた。