But the dominant cause of this war is to be found in political ambitions rather than in religious passions, and if we must declare who of the two was the aggressor, it is difficult to escape throwing the blame upon Constantine. Licinius was advancing in years. Even if he had not outlived his ambitions, he can at least have had little taste for a campaign in which he put all to the venture. Constantine, on the other hand, was in the prime of life, and the master of a well tried, disciplined, and victorious army. The odds were on his side. He had all the legions which could be spared from the Rhine and the Danube, and all the auxiliaries from the Illyrian and Pannonian provinces—the best recruiting grounds in the Empire—to oppose to the legions of Syria and Egypt. Constantine doubtless seemed to the bishops to be entering the field as the champion of the Church, but the real prize which drew him on was universal dominion. This time both Emperors exerted themselves to make tremendous preparations for the struggle. Zosimus describes how Constantine began a new naval harbour at Thessalonica to accommodate the two hundred war galleys and two thousand transports which he had ordered to be built in his dock-yards. He mobilised, if Zosimus is to be trusted, 120,000 infantry and 10,000 marines and cavalry. Licinius, on the other hand, is said to have collected 150,000 foot and 15,000 horse. Whether these numbers are trustworthy or not, it is evident that the two Emperors did their best to throw every available man into the plain of Adrianople, where the two hosts were separated by the river Hebrus. Some days were spent in skirmishing and manœuvring; then on July 3, 323, a decisive action was brought on, which ended in the rout of the army of Licinius. Constantine, whose tactical dispositions seem to have been more skilful than those of Licinius, secretly detached a force of 5000 archers to occupy a position in the rear of the enemy, and these used their bows with overwhelming effect at a critical moment of the action, when Constantine himself, at the head of another detachment, succeeded in forcing a passage of the river. Constantine received a slight wound in the thigh, but he had the satisfaction of seeing the enemy driven from their fortified camp and betake themselves in hurried flight to the sheltering walls of Byzantium, leaving 34,000 dead and wounded on the field of battle.