Ali al-Ridha succeeded to his father's property but not fully to his title. He began to teach and issue fatwas from the mosque in Medina, where he lived, but the caliphs did not confirm his title and many of his father's trustees withheld their support (and tithes) under the pretense that his father would soon return as the Mahdi.[3] Following Harun's death in 809, a civil war broke out between his sons Al-Amin and Al-Ma'mun. Al-Amin was beheaded in September 813 during the siege of Baghdad[6] but his followers continued their resistance under local governors or in favor of Al-Ma'mun's uncle as late as 827.