The concept of the Tetrarchy until arrival of Diocletian was nothing new in the ancient world. However, the Tetrarchy this work speaks about is a novelty – it speaks about the introduction of the Tetrarchy as a collegial government. We studied the introduction of a single system that is based on unity and harmony among the four emperors who have perceived themselves as fathers and sons, brothers. We addressed the context from the arrival of Diocletian to power to his abdication, considering him as a person that is most responsible for the introduction of such a system. Many of the scholars, from Cambi to Finley, agree that the introduction of this system of government is something that saved the Empire from rapid deterioration. The introduction of such a system enabled the Empire to take a breath between the two rounds of the historical arena and get ready for a new clash and the rush of barbarians. Gallic tribes in the Northeast, Carausius in Britain, Achilles in Egypt, Quinquegentiani tribes in Africa, Narses of Persia, Germans who are advancing over the Danube limes... There was almost no part of the Empire that was not just waiting to burst under the pressure of emerging threats – Diocletian, aware that he can not cope with all of these problems on his own, created a divine system of Jupiter and Hercules Seniors and Juniors to stop the decadence of the Empire, with iron and blood.