In particular a Sayyid called Ibn Ishaq (d. 1805) raised the standard of rebellion and claimed the imamate from 1781 to 1785, assisted by Arhab tribesmen.
During the next three years he conquered the Tihamah from the imam, while Abu Nuqta performed raids into the territory still loyal to the Zaidi state.
Al-Mansur Ali I prepared an expedition to Tihamah in 1806, but it never got underway; the event indicates the weakness of the Zaidi imamate at this time.
The well-known religious scholar Muhammad ash-Shawkani, who was his grand qadi, wrote favourably of him, while other texts assert that he left governance to his ministers and kept busy with building activities and womanizing.
The wazir Hasan al-Ulufi who kept the real powers in San'a was arrested by the old imam's son Ahmad, who took over the administration in 1808.