Bishr is not mentioned again in the medieval sources until 743/44 when he became involved in the internecine struggle over the caliphate between the Umayyad dynasty.[1] To that end, he fought against his cousin Caliph al-Walid II in support of his brother, Yazid III, despite warnings from his other brother and prominent wartime general, al-Abbas, to remain neutral.[1] An account by Bishr's unnamed son of Bishr's disagreement with al-Abbas was recorded in the history of 9th-century historian al-Tabari.[4] Twelve other brothers of Bishr likewise supported Yazid III,[1] who went on to become caliph after al-Walid II's assassination in 744. Yazid III ruled for a few months before dying and being succeeded by his brother Ibrahim, who months later, in 745, surrendered the caliphate to Marwan II. At the time of the latter's accession, Bishr had been serving as governor of Jund Qinnasrin (military district of Qinnasrin) in northern Syria.[1] Marwan II subsequently compelled the largely Qaysi troops of Qinnasrin to arrest and hand over Bishr and the latter's full brother Masrur who became captives.[1] They are not heard of again and are assumed to have died in prison.[1]