Originally a military slave (ghulam or mawla) who served under the future al-Mu'tadid in the suppression of the Zanj Rebellion, his ability and loyalty led him to become the Caliph's commander-in-chief, exercising considerable influence in the governance of the state throughout Mu'tadid's reign.
[4] During the Zanj war, the ghilman, often with the young Mu'tadid at their head, played the main role in the fighting, providing the Abbasid armies with a professional core, filling leadership positions, and undertaking the most difficult assaults.
Already on Mu'tadid's succession of his father as regent of the Caliphate in June 891, Badr was named as chief of security (sahib al-shurta) of Baghdad.
Qasim then enticed him to return to Baghdad by a guarantee of safe passage (aman), but on 14 August 902 at al-Mada'in, the vizier's agents attacked Badr while he was praying and cut off his head to send to the Caliph.
[10][13] The murder of Badr was criticized by the poets of the time, and even the Caliph, "who might have been expected to heave a sigh of relief at seeing the head of the once-powerful general", is said to have reproached Qasim for it.