While in Diocletian’s court Constantine fought in Asia and Assyria. This gained there trust because his father was a ruler that Diocletian never really trusted. In late spring 305 Constantine’s father requested him to leave Diocletian’s court and help him campaign in Britain the request was only granted because of a long night of drinking. When Diocletian woke in the morning it was too late for Constantine had fled to far and joined with his father in before the summer. After a year at his father’s side he sent Diocletian a note of his father’s death and declared himself the new ruler of his father’s old territory. Diocletian could not refuse because he knew it would mean out right war and Constantine now had control of one of Rome’s largest armies. (http://en.wikipedia.org/wiki/Constantine_the_Great).
When Constantine became the sole ruler of the west of the empire he returned all that the Christians had lost during the persecution. He sponsored many building projects in Gaul and fortified the military protection around its cities. His counterpart and ruler of the east became jealous of Constantine and started a civil war against him. Maximian rebelled against Constantine now sole ruler of the Roman Empire in 310ad. He pretended Constantine had died in his campaign against the Franks taking up the power of the empire. When Constantine caught ear of this he marched his army back to Rome. This caused Maximian to flee he was caught reproved for his crimes. Constantine gave some mercy but strongly encouraged his suicide and in July 310 Maximian hung himself (http://en.wikipedia.org/wiki/Constantine_the_Great).
Another civil war was planned against him by the middle of 310 by Maxentius. He fortified northern Italy and gained the Christians help by stopping their persecution and allowing them to elect a new Bishop. When Constantine marched on Maxentius his soldiers had crosses on the shields they carried because he had a vision the night before and being a Christian now followed it. The battle was brief as if god was on his side and he won. (World Book Ci-Cz. Chicago: World Book inc, 2006).
Constantine being the first Roman Emperor to be a Christian did a lot of good for our faith. He gave Christians freedom again and legalized the church and was even regarded as a saint by the Eastern Orthodox Church. He built the first great cathedral the Lateran Basilica in Rome. He also built other