Following the death of Constantius Chlorus, who served as Roman emperor in the Western provinces, his son, Constantine I, was proclaimed emperor by the troops stationed in York, England. This moment marked not only a personal leap for Constantine but also initiated a significant shift in the political landscape of the Roman Empire. With familial ties to the ruling emperor, he had strong claims for legitimacy, which were solidified by the military's backing. The proclamation took place in a chaotic environment, as rival factions and individuals vied for control amid the declining stability of the empire. The support from his army was crucial, as securing loyalty from military leaders and their troops often determined the success of any aspiring authority during this period.

Constantine's rise was catalyzed by his military experience, as he had been involved in campaigns across various regions. His leadership qualities helped unify his troops, creating a cohesive force that would further his ambitions. His ascendance to power initiated a series of events that would eventually lead to the establishment of a more centralized and administrative government in the empire. Ruling for nearly three decades, Constantine would later move the capital to Byzantium, renaming it Constantinople, signifying a pivotal evolution in Roman governance and its influence over Europe and the Mediterranean regions.

Moreover, Constantine's reign would be characterized by significant reforms including the promotion of Christianity within the empire, a transformative decision that reshaped the cultural and religious identity of Europe. This set a precedent for the interplay between politics and religion that would characterize the following centuries. The events surrounding his proclamation were not merely a struggle for power but also an indication of the shifting sands in Roman authority as new leaders emerged and old structures began to dissolve.