Cleon's personal ineptitude became his downfall. Wishing to thank a gardener, Mandel Gruber, for his part in thwarting an assassination attempt on Dr. Seldon, he promoted Gruber to chief gardener over the Imperial Palace grounds. Gruber, not wishing to abandon his lifestyle of being out in the open for the head gardener's administrative role, had a mental breakdown and shot the Emperor. The chaotic upset which followed Cleon's assassination saw the rise of a military junta and Hari Seldon's retirement from overt politics.