After a sojourn in Medina he returned to the Zaidi capital in Yemen, Sa'dah, where he was chosen to succeed his brother al-Murtada Muhammad in September 913.
[1] He was considered an efficacious ruler; one of his adherents composed a panegyric text which described the imam as the one who strengthened Islam after it had become weak.
[2] The long reign of an-Nasir Ahmad was filled with struggles against the adherents of the Fatimids, who also had a strong following in parts of Yemen.
In January 920 he met the Ismailite leader Abd al-Hamid of Jabal Maswar in a three-days battle at Nughash outside San'a.
[3] He left six sons, called al-Mukhtar al-Qasim, Isma'il, al-Muntakhab al-Hasan, Ja'far, al-Mansur Yahya, and Ali.