What role did emperor Constantine do to change the roman empire?

For the most part, Constantine retained most of the sweeping reforms introduced by his predecessor, Diocletian, and which restructured the Roman Empire: the doubling in the number of provinces of the empire and the their grouping into 12 dioceses and the doubling of the size of the imperial bureaucracy.

To address the problem of hyperinflation which had plagued the em[ire, Constantine temporarily dropped the main silver coin, the denarius, and concentrated on minting a gold coin the aureus). To do this he resorted to confiscating the treasuries of temple and their gold statues to smelt gold. Historians disagree on whether the Aureus was introduced by Constantine or his predecessor. The problem of hyperinflation had been caused by decades of debasement of the Roman coins (i.e. the reduction of their precious metal content. This devalued the Roman coins and caused inflation. The aureus had a high content of gold and was never debased over the next centuries. This, over the long run, resolved the problem of inflation.

Historians also disagree on whether a military reform of this period was carried out by Constantine or Diocletian. Previously the Roman Army had legions which were stationed in the provinces, particularly the frontier ones, and were under the command of provincial governors. The army was now divided into frontier troops, the limitanei, and the comitatus, the field army. The task of the limitanei was to respond to smaller scale hold attacks on the frontier. The comitatus supported the limitanei when there were larger scale invasions, carried out large scale operations in foreign territories. The comitatus and was composed of the legiones (legions) comitatenses . They were regional units stationed in each of the new administrative regions created by Diocletian (the dioceses), further back from the frontiers and near cities. They were mobile units and they were more heavily armed. They could be deployed rapidly. The size of the legions was decreased from some 5,000 to 1,000 and their number was increased.

Constantine favoured Christianity. With the Edict of Milan, issued together with his co-emperor Licinius in 313, he finalised the termination of the Great persecution of the Christians which had been decreed by the Edict of Toleration by the emperor Galerius two years earlier. C

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built Christian churches, most notably, the original Basilica of St Peter's in Rome, the St John Lateran's Basilica (the city of Rome's first Cathedral and the original residence of the Popes), the Church of the Holy Apostles in Constantinople and Church of the Holy Sepulchre in Jerusalem. He convened synods and ecumenical councils to mediate disputes between rival Christian doctrines, and initiating the tradition of Roman emperors convening such meetings.He promoted Christians in the imperial bureaucracy.