Ever since the fall of the Severan dynasty, which ruled the Roman Empire between 193 and 235, rivals for the imperial throne had bid for support by either favouring or persecuting Christians. During the following period known as the crisis of the Third Century (AD 235–284) the Roman Empire nearly collapsed under the combined pressures of invasion, civil war, plague, and economic depression. The Crisis began with the assassination of Emperor Alexander Severus at the hands of his own troops, initiating a fifty-year period in which 20–25 claimants to the title of Emperor, mostly prominent Roman army generals, assumed imperial power over all or part of the Empire.