The night Commodus was strangled
On 31 December 192 an athlete named Narcissus strangled the emperor in his bath. The Antonine dynasty ended there, and with it a century of orderly succession.
An emperor turned Hercules
The last years of Commodus were one continuous performance. He fought in the arena, renamed Rome after himself, and had himself shown as Hercules, club on shoulder and lion skin over his head.
This is not merely the report of hostile historians: the coinage confirms it. The aurei and medallions of 191 and 192 carry the Herculean legends, HERCVLI ROMANO AVGVSTO, and the hero's attributes. A coin is an official document: what the emperor has engraved on it, he is claiming.
The plot
Poison having failed, the palace conspiracy — his concubine Marcia, the chamberlain Eclectus, the praetorian prefect Laetus — turned to a training partner to strangle him. The Senate voted damnatio memoriae at once and proclaimed Pertinax.
Eighty-seven days later Pertinax was killed by the praetorians, who put the empire up for auction. Didius Julianus won it, lasted two months, and four claimants fought over power in 193.
What numismatics retains of it
The damnatio did not melt down all of Commodus's coinage: it remains common, sestertii in particular. The issues of 193, on the other hand, are among the rarest of the period. A denarius of Pertinax or of Didius Julianus costs several hundred euros, not for its beauty but for the brevity of the reign that produced it.
This is a general rule for the period: rarity follows the duration of power, almost mechanically.
Further reading
Dio Cassius, Roman History, book LXXIII, the testimony of a contemporary senator.
O. Hekster, Commodus. An Emperor at the Crossroads, Amsterdam, 2002.