Editor's note: this is the second part of a series by Coin World Senior Editor Jeff Starck about the ancient coins from the Year of Five Emperors. This story appeared in the December issue of Coin World.

The assassination of Pertinax ushered in what David Vagi (writing in Coinage and History of the Roman Empire) considers the lowest event in Roman history. 

The right to rule the empire was sold at a public auction by the praetorian guards — the very men responsible for the emperor’s protection. 

“The highest bidder was Didius Julianus, a wealthy nobleman who had more money than scruples,” wrote Vagi in the article.

His winning bid was 25,000 sestertii per guard, a huge sum that Pertinax’s father-in-law, Flavius Sulpicianus, could not beat. 

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“Drunk with power and blinded by greed, the praetorians conducted Julianus in tight formation to the senate house, where the terrified senators had little choice but to hail him emperor,” wrote Vagi in his book.

Though wealthy and ambitious, Didius Julianus was not up to the task, failing to deliver his remuneration to the praetorian guards and unable to oppose rebellions that flared up from generals in the provinces.

Public rage prompted the rebellions, as citizens immediately sought the assistance of frontier commanders to break free from the reign of the guards and this emperor. 

Three generals responded to the people’s pleas: Clodius Albinus, Pescennius Niger, and Septimius Severus.

Severus was stationed at Carnuntum, a legionary stronghold in the northeastern part of modern Austria, only a few days’ march from the capital.

He commanded more than three legions in Pannonia and soon gained the support of the remaining legions stationed along the Rhine and Danube rivers, totaling more than 16 legions. The praetorian guards would be no match for the seasoned Pannonian legions commanded by Severus. 

Julianus made last-ditch efforts to spare his hide, sending assassins after Severus and even offering to share power with him, but to no avail. To avoid bloodshed, Severus promised immunity to members of the praetorian guard for “ratting out” the men who killed Pertinax. The guards agreed and the senate confirmed the change in power, condemning Didius Julianus and declaring Septimius Severus the new emperor. 

On June 1 or 2, 65 or 66 days after buying the throne, Didius Julianus was beheaded, ending his brief and controversial reign. 

Coinage of Didius Julianus consists of standard imperial issues in all three metals, though they are even more difficult for collectors to locate than the coins of Pertinax. 

A Nearly VF bronze sestertius of Julianus realized $426.53 (including fee) in Heritage’s April 10, 2014, auction. In that same 2014 auction, a silver denarius of Julianus (graded EF by NGC, 4/5 for strike and 3/5 for surface) realized $3,055 with the fee. 

Gold examples are also extremely expensive: Fritz Rudolph Künker auctioned an EF/Near EF example on Oct. 2, 2015, realizing a hammer price of €150,000 ($167,516). The buyer’s fee ranges from 20 to 23 percent, based on bidding and payment method.