How did Muhammad Bello become the leader of the Sokoto caliphate after Usman dan Fodio’s death?

Following the death of Usman dan Fodio in 1817, his son Muhammad Bello succeeded him as the amīr al-muʾminīn (commander of the faithful) of the Sokoto caliphate.12

Prior to this transition, Muhammad Bello and his uncle Abdullahi dan Fodio had already played central roles in the administration and expansion of the caliphate. In 1812, the caliphate’s administration was formally reorganized, with Bello and Abdullahi serving as the two principal viziers responsible for the eastern and western sectors, respectively. Upon Usman dan Fodio's death, while Muhammad Bello assumed the leadership of the caliphate, Abdullahi was designated as the emir of Gwandu, taking charge of the western emirates.312