The Battle of Lugdunum, also called the Battle of Lyon, was fought on 19 February 197 at Lugdunum (modern Lyon, France), between the armies of the Roman emperor Septimius Severus and of the Roman usurper Clodius Albinus. Severus' victory finally established him as the sole emperor of the Roman Empire following the Year of the Five Emperors and immediate aftermath. This battle is said to be the largest, most hard-fought, and bloodiest of all clashes between Roman forces. According to English historian Edward Gibbon, the Roman historian Cassius Dio placed the total number of Roman soldiers engaged for both sides combined at 150,000. Historian Michael Kulikowski states that Severus led the much larger force with the combined legions of Dacia and the Danubian provinces. Historian A. J. Graham supports Gibbon's number of 150,000 soldiers in total, rather than the sometimes cited number of 300,000 in total and therefore 150,000 on each side, which he states to be a commonly accepted mistranslation of Cassius Dio's original language. Graham also analyses the possible forces available to Albinus and states that the numbers on each side could have been roughly equal. Background Following the murder of Emperor Pertinax by the Praetorian Guards on 28 March 193 after a reign of only 3 months, a struggle began for the succession to the throne of the Roman Empire, resulting in the Year of the Five Emperors. After the murder of Pertinax, despite the dismay and demonstrations of the plebeians, the praetorians auctioned the empire to the highest bidder, Didius Julianus. The disenchanted Roman crowd called out the name of Pescennius Niger, governor of Roman Syria, who controlled three legions, to come to Rome to take over. When Pescennius Niger heard the news of Pertinax's death, he proclaimed himself emperor and gained the support of 10 legions in total. Meanwhile, Septimius Severus, governor of Pannonia Superior, and also a commander of three legions, had been proclaimed emperor by his legions. Severus promised to avenge the murder of Pertinax, who had been held in high regard by the soldiers. Before moving on Rome to overthrow Didius Julianus, Severus made an alliance with the powerful commander of the three legions and 70 auxiliary regiments in Britannia, Clodius Albinus Severus recognized Albinus as Caesar and apparent heir to himself as Augustus. Albinus accepted this arrangement. Severus, who was located closer to Rome than Pescennius Niger, soon gained the support