Al-Mansur Ali I was an Imam of Yemen who ruled in 1775–1809.
Background
He belonged to the Qasimid family, descended from the Islamic prophet, Muhammad, which dominated the Zaidi imamate in 1597–1962. During the reign of his father he was governor of San'a. After his father's death he successfully claimed the imamate, taking the name al-Mansur Ali.
Career
Ali bin Abbas was one of about 20 sons of Imam al-Mahdi Abbas (d 1775). He led a number of successful military expeditions against warring tribes. His first twenty years in power were marked by periodical petty wars with unruly tribesmen.
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. Al-Mansur Ali I managed to deal with these crises. The character of al-Mansur Ali I is debated among the chroniclers.
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. On the other hand, he was considered brave, generous and hospitable. By the early 19th century his faculties began to fail, and intrigues arose at court while chaos reigned in the land.
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. He managed to appease the dissatisfied tribesmen who had performed raids around San'a.