whatsoever in the seat of the heavens". Daza in the meantime decided to attack Licinius. Leaving Syria with 70,000 men, he reached Bithynia, although harsh weather he encountered along the way had gravely weakened his army. In April 313, he crossed the Bosporus and went to Byzantium, which was held by Licinius' troops. Undeterred, he took the town after an eleven-day siege. He moved to Heraclea, which he captured after a short siege, before moving his forces to the first posting station. With a much smaller body of men, possibly around 30,000, Licinius arrived at Adrianople while Daza was still besieging Heraclea. Before the decisive engagement, Licinius allegedly had a vision in which an angel recited him a generic prayer that could be adopted by all cults and which Licinius then repeated to his soldiers. On 30 April 313, the two armies clashed at the Battle of Tzirallum, and in the ensuing battle Daza's forces were crushed. Ridding himself of the imperial purple and dressing like a slave, Daza fled to Nicomedia. Believing he still had a chance to come out victorious, Daza attempted to stop the advance of Licinius at the Cilician Gates by establishing fortifications there. Unfortunately for Daza, Licinius' army succeeded in breaking through, forcing Daza to retreat to Tarsus, where Licinius continued to press him on land and sea. The war between them ended only with Daza's death in August 313. Given that Constantine had already crushed his rival Maxentius in 312, the two men decided to divide the Roman world between them. As a result of this settlement, the Tetrarchy was replaced by a system of two emperors, called Augusti: Licinius became Augustus of the East, while his brother-in-law, Constantine, became Augustus of the West. After making the pact, Licinius rushed immediately to the East to deal with another threat, an invasion by the Persian Sassanid Empire. Conflict with Constantine I In 314, a civil war erupted between Licinius and Constantine, in which Constantine used the pretext that Licinius was harbouring Senecio, whom Constantine accused of plotting to overthrow him. Constantine prevailed at the Battle of Cibalae in Pannonia (8 October 314). Although the situation was temporarily settled, with both men sharing the consulship in 315, it was but a lull in the storm. The next year a new war erupted, when Licinius named Valerius Valens co-emperor, only for Licinius to suffer a humiliating defeat