Bel Riose was the last great general of the Galactic Empire, serving under Cleon II. He dreamed of glory and often expressed a negative opinion towards the Empire's cultural and technological decline.
Riose learns of the Foundation from Ducem Barr, a noble of the planet Siwenna. Correctly interpreting Barr's tales of "magicians" as the remnants of science in the Periphery, and witnessing some scientific advances made by the Foundation itself in the form of a personal force-shield, he decides to conquer the Foundation and utilize its scientific resources to revitalize the dying Empire. En route to the Foundation, he captures one of its Traders, Lathan Devers, and holds him hostage alongside Barr in an attempt to gain intelligence over the Foundation.
Although Devers and Barr escape Riose and make their way to Trantor in an attempt to gain an audience with the Emperor, the forces of history make their efforts meaningless. Fearing Riose's power, Cleon II orders him back to Trantor and has him executed for treason, as per Hari Seldon's prediction that by the end of the Empire, any military officer who was to gain enough power to threaten the Foundation would be prevented from causing harm by the central government's own fear of rebellion.