Constantine had, in a previous war (in 316), defeated Licinius at the Battle of Cibalae and conquered from him the entire Balkan Peninsula, with the exception of Thrace. A peace had been arranged but the relationship between the two emperors remained uneasy. By 324 Constantine was ready to renew the conflict, and when his army, in pursuit of a raiding force of Visigoths, or possibly Sarmatians, crossed into Licinius' territory, an opportune "casus belli" was created. The reaction of Licinius to this incursion was overtly hostile, inducing Constantine to go on to the offensive. Constantine invaded Thrace in force; his army was smaller than that of Licinius, but it contained many battle-hardened veterans and, as he had control of the Illyrian region, the finest quality new recruits.