Vadomarius

thumb|upright=1.1|Area settled by the Alemanni, and sites of Roman-Alemannic battles, 3rd to 6th centuries Vadomarius () was an Alemannic king and Roman general, who shared power with his brother Gundomadus. After instigating an indecisive campaign in Gaul against the Romans, Vadomarius and his brother signed a treaty with the Roman emperor Constantius II in AD 356. Encouraged by Constantius II, Vadomarius employed his Alemanni forces in an attack against Julian (Constantius' Caesar who had revolted against his rule). Vadomarius then concluded a treaty with Julian, after which, he unsuccessfully attempted to play the two Roman figures against one another. When Julian was made aware of this, he arrested Vadomarius and banished him to Hispania. His son Vithicabius succeeded him as king. Later, Vadomarius allied himself with Rome under emperors Jovian and Valens, leading his forces against the usurper Procopius and fighting the Persians on Rome's behalf.

==Life== The life of Vadomarius is best documented by the Roman historian Ammianus Marcellinus. According to his writings, Constantius II explicitly went to Valentia to wage war against Vadomarius and Gundomadus, whose forces had been laying waste to parts of Gaul. In 356, Vadomarius and his brother Gundomadus concluded a peace treaty with the Romans after having lost a battle against emperor Constantius II. thumb|right|The emperor Constantius II (ruled 337–61), Julian's cousin and superior. One of the three sons and successors of [[Constantine I the Great, he survived his two brothers to become sole emperor in 350. He is portrayed with a halo, as were most Christian emperors of the period. Portrait on a manuscript of the Chronography of 354, Rome]]