May 21 is the 141st day of the year (142nd in leap years) in the Gregorian calendar; 224 days remain until the end of the year. == Events == === Pre-1600 === 293 – Roman Emperors Diocletian and Maximian appoint Galerius as Caesar to Diocletian, beginning the period of four rulers known as the Tetrarchy.
May 21 is the 141st day of the year (142nd in leap years) in the Gregorian calendar; 224 days remain until the end of the year. == Events == === Pre-1600 === 293 – Roman Emperors Diocletian and Maximian appoint Galerius as Caesar to Diocletian, beginning the period of four rulers known as the Tetrarchy.
Source: Wikipedia "May 21" · CC BY-SA 4.0
Share this article: X · Bluesky