Pertinax: ADE 193-193

 After Commodus was strangled to death by his personal wrestler, the power of the principate was shifted to an elderly senator named Publius Helvius Pertinax. Although the Praetorian Guard secured him the Emperorship, Pertinax's firm discipline and lack of monetary bonuses to the Praetorian Guard caused his downfall. Within in three months of rule, Pertinax was murdered by a group of disgruntled Praetorians on March, 193. What came next was one of the most disturbing events in a long line of selfish deeds undertaken by the Praetorian Guard. For a promise of 25,000 sesterces, the Emperoship was auctioned off to a wealthy senator by the name of Marcus Didius Julianus.