Given the task definition and input, reply with output. In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

During this man's reign, the Gregorian law code was issued, while his economic reforms included the creation of seven new mints and instituting the iugum and capitatio taxes. His armies put down the Bagaudae revolt in Gault, the attempts of Achilleus and Domitius Domitianus to make Egypt independent, and the British usurper Carausius. This issuer of the Edict of Maximum Prices won a battle for supremacy at the (*) Margus. He rose to power after executing Aper, supposedly fulfilling a prophecy about killing a boar, during a campaign against Persia in which Numerian died mysteriously. After disposing of his rival Carinus, he established Sirmium, Trier, Milan and Nicomedia as subsidiary capitals. Lactantius was not a big fan of one of this man's policies, and he built a palace at Split in Croatia that he retired to. This emperor installed Maximian, Galerius, and Constantius Chlorus to high positions, and he instigated a major purge of Christians. For 10 points, name this Roman emperor who resolved the Crisis of the Third Century by creating the augustus-caesar system or tetrarchy.
History