Diocletian was Roman Emperor from November 20, 284 to May 1, 305.
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Diocletian
Gaius Aurelius Valerius Diocletianus (c. 245–c. 312) ended the "Crisis of the Third Century" (235–284) by giving up sole control of the Empire, thereby ending the Principate and setting up the rule by 4 known as the Tetrarchy. Instead of dying in office, as all earlier emperors had done, Diocletian retired.