The lowest point of the succession problems was actually not during the long troubled years, but in 193 C.E. After the emperor Commodus was assassinated (by a professional wrestler), there was no obvious successor. The Praetorian Guard auctioned the throne off to a senator named Didius Julianus. Unfortunately for Julianus, he had no military support and was killed a few months later in the face of the advance of Septimius Severus, a real general.

Source: Chris Scarre, Chronicle of the Roman Emperors (London: Thames & Hudson, 1995).