Mansur aligned himself with Zahir al-Umar and Ali Bey, the autonomous rulers of Galilee and Egypt, respectively, in their rebellion against the Ottomans.
Mansur was subsequently forced by the Druze sheikhs of Mount Lebanon to step down in favor his nephew Yusuf Shihab after Zahir and Ali Bey were defeated in 1770.
Jumblatt attempted to mediate the dispute between the uncle and nephew, but Mansur dismissed the gesture and seized Yusuf's properties.
Jumblatt subsequently defected from Mansur's camp and gave his backing to Yusuf, who also approached Uthman Pasha al-Kurji, the governor of Damascus for support.
According to a later Lebanese chronicler, Mansur "much loved Zahir al-Umar and rejoiced" at his joint invasion of Syria and Palestine with Ali Bey.