From the time that Constantine’s (AD 227-337) father died (306) until Constantine challenged Maxentius at Milvian bridge (312), he was consolidating his position of power in Gaul and Britain. Even at this early date he showed the same military and political acumen that he would later exhibit as emperor: He strengthened his defenses against the barbarians along the Rhine, winning the gratitude of his French subjects. He did not impose onerous taxes on the people, and entertained the bloodthirsty among them with frequent shows in the circuses He was deft in diplomacy and military strategy. Above all, he was a patient man, not playing his hand until the time was right.
At the Battle of Milan (312) Constantine prepared for his invasion of Italy by making sure that Licinius could not take advantage of it by seizing Maxentius’s territories to the East. To that end, he offered Licinius his half-sister Constance in marriage, and waited until Licinius was militarily engaged with Maximinus Daia before launching his own campaign. He committed only ¼ of his troops to the battle – the rest remaining in Gaul to ward off barbarian advances. Upon winning the battle and gaining control of the western half of the empire, Constantine moved to consolidate his power, entering into an alliance with Licinius in 313 (the “Edict of Milan”).