with Albinus, Severus gave himself the name Petrinax to avenge the recently murdered emperor. Severus marched on Rome and disbanded the Praetorian guard with his own installment. The tension between Severus and Albinus' contest to usurp the Roman Empire's throne resulted in the Battle of Lugdunum (modern day Lyon) on 19 February 197. According to Cassius Dio's Roman History Severus and Albinus were equally armed with 150 000 soldiers on both sides at Lyon. The skirmish went back and forth but the decisive collapse of Albinus' left wing turned the battle in favor of a Severus victory. Once he realized that his defeat was imminent Albinus committed suicide giving Severus total control of the Roman Empire. The split of Roman Britain According to Roman historian Herodian's work History of the Empire, Severus split Roman Britain into Upper and Lower provinces soon after the Battle of Lugdunum. However there is still confusion among historians as to the exact date and circumstances behind the division of Roman Britain. A.J. Graham argues this matter of doubt is due to a considerable lack of evidence for Herodian's division date of 197AD. Related evidence of Legion lists by Cassius Dio could possibly be used to confirm Herodian's claims but Dio's inscriptions are undated. Graham concludes that Severus did not split Roman Britain himself. Instead Graham argues the split would have officially taken place under the power Severus' co-emperor Caracella sometime between 211 and 220 AD. Graham concludes that although the specifics of the division are inconclusive the nature of the split is still important. The distinction of Superior and Inferior is important because the inferior Lower Britain lay in the northernmost part of the province. This fact reveals Caracella's passive nature of agreement and retreat with the Maetian barbarians beyond the Roman border. Epigraphical evidence shows that an inscription made during the time of Lucius Julius Julianus between 198-209 AD describes his legions being based at Carleon in what was to become Upper Britain. This leads historians to believe Britain had still not been divided by 209 AD. This is also evidence that although less legions were in the north, Lower Britain relied on soldiers from the south. Evidence pointing towards the existence of a southern concord serving near Corbridge in Lower Britain exists. Another altar devoted to a southern commander proves that detachments of two Upper Britain legions were serving together on the northern