Europe 366: Usurpation of Marcellus
Procopius’ revolt collapsed remarkably quickly in spring 366, with his troops defecting to Valens in the battles of Thyatira and Nacolia. Learning of Procopius’ execution, his kinsman Marcellus attempted to succeed him, but was shortly afterwards arrested by forces arriving from the west.
366 Battle of Cabillonum▲
In the winter of early 366, the Alemanni crossed into Gaul in great force and plundered many regions. The Roman counts Charietto and Serverianus marched out to meet the invaders, but, in a battle by a stream near Cabillonum (Chalon-sur-Saône), the Alemanni broke through the Roman line and killed both counts. At this, the Romans fled, temporarily losing the standard of the Eruli and of the Batavi to the enemy.
May 366 Battle of Thyatira▲
In spring 366 Valens marched out against the usurper Procopius and, by placing the respected old general Arbetio—a veteran of Constantine the Great’s campaigns—in command of his forces, successfully awed the rebel army in Lycia into defecting. Valens then headed north, where he met Procopius in battle near Thyatira. Here Procopius appeared to be gaining the advantage, when Gomarius, one of his generals, suddenly abandoned his master and, together with much of the army, also defected to Valens.
366 Jovinus’ Gallic campaign▲
Shocked by the news of the Alemannic victory at Cabilonnum in early 366, Valentinian appointed Jovinus as Magister Equitum and dispatched him to deal with the situation. Jovinus marched to the Meuse, where he recaptured the Roman fort of Scarponna and massacred a number of Alemanni along the river. He then met a major Alemannic force at Châlons-en-Champagne, which he defeated in a day-long battle, inflicting some 10,000 casualties for 1400 Roman losses. As the broken invaders fled over the following days, some legions caught and arbitrarily hanged the Alemannic leader, effectively bringing the campaign to an end.
26 May 366 Battle of Nacolia▲
After his defeat at Thyatira, Procopius fled east to Nacolia, where he met Valens in a final battle in late May 366. Once again, Procopius’ army faced defection, this time led by the general Agilon, and the usurper was forced to flee for the hills. He was betrayed to Valens the following morning by his two remaining followers, Florentius and Barchalbas, and immediately beheaded.
Jun 366 Usurpation of Marcellus▲
When Procopius’ kinsman Marcellus heard of the usurper’s death in May 366, he quickly seized power in Chalcedon. At the same time, however, Equitius invaded Thraciae from Illyricum on behalf of Valens and, learning of Marcellus’ usurpation, sent a body of troops across the straits to arrest him. Quickly imprisoned, Marcellus was killed some days later as part of Valens’ ruthless purge of anybody associated with Procopius’ revolt.