The stories about the emperor's vision and dream before the battle outside Rome were Constantine's own memories. Distinguishing those stories from the commentary in which Eusebius subsequently embedded them in Life of Constantine has interesting implications. One is that it is possible to detect some of the influences that independently shaped Constantine's memories and Eusebius' commentary. Although the memories and the commentary converged in Eusebius' Life, until that moment they had followed separate tracks. The emperor's memories and the bishop's commentary each had a distinct backstory.

After the battle and his return to Gaul early in the following year, Constantine remained in the western provinces. He continued to campaign along the Rhine frontier; he returned to Rome in 315; and after seizing the Balkans from Licinius, he campaigned along the Danube frontier. The backstory for his memories hence included his subsequent experiences in the West, as well as various accounts of the battle that he heard, read, or viewed (Chapters 6–7). In contrast, the backstory for Eusebius' commentary in Life consisted largely of his own earlier accounts. For modern historical analysis, disentangling these earlier accounts becomes an opportunity to see Eusebius at work as a historian and an apologist. His narrative in Life of Constantine's victory at Rome was not his first account of the battle. Nor was it his second account. In fact, it was not even his third account.