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.
[3] Julian's rise to power and Vadomarius' decision to stand by Constantius II was likely the result of intimidation, which subsequently led him to join and lead the Alamannic coalition in AD 357.
[6] However, Julian's military power was greater than expected and in 359, he crossed the Rhine near Mainz with his forces and scattered his enemies; thereafter he concluded peace treaties with the Alemannic kings Vadomarius, Macrian, Hariobaudes, Urius, Ursicinus and Vestralpus.
[13] Under emperor Valens, Vadomarius employed siege-warfare techniques he would have learned as a Roman soldier to besiege the supporters of the usurper Procopius in Nicaea.
"[16] The story of both Vadomarius and his son reveal the manner in which Romans handled their barbarian neighbors, co-opting and recruiting them when it suited their needs but against whom they often used treacherous means.