From Wikipedia, the free encyclopedia

The anno Diocletiani era or the Diocletian era or the Era of Martyrs is a method of numbering years used by Alexandrian Christians during the fourth and fifth centuries. Western Christians were aware of it but did not use it. It was named for the Roman Emperor Diocletian who instigated the last major persecution against Christians in the Empire. As Diocletian began his reign during the Alexandrian year beginning on August 29, 284, year one began on that date. The era was used to number the year in Easter tables produced by the Church of Alexandria. When Dionysius Exiguus continued those tables for additional 95 years, he replaced the anno Diocletiani era with his anno Domini era because he did not wish to continue the memory of a tyrant who persecuted Christians. The anno Domini era became dominant in the Latin West but was not used in the Greek East until modern times.

The anno Diocletiani era was not the only one used by early Christians. Most Roman Christians designated their years by naming the two consuls who held office that year. The AUC year was rarely used. Some Eastern Christians had used an era that began at the birth of Jesus in the second and third centuries. It was soon replaced by eras that began at Creation, called anno Mundi eras, which became the dominant method of numbering years in the East until modern times. Annianus of Alexandria, a monk who flourished at the beginning of the fifth century, placed the epoch of his world era on 25 March 5492 BC by counting back eleven 532-year paschal cycles from anno Diocletiani 77, itself four 19-year lunar cycles after anno Diocletiani 1. Regarded as a civil rather than a religious era, it began on the first day of the Alexandrian year, 29 August 5493 BC. This Alexandrian era was the preferred era used by Byzantine Christians such as Maximus the Confessor until the Byzantine era, having an epoch of September 1, 5509 BC, became dominant in the tenth century. Both eras used a version of dating Creation based on the Septuagint. Christians in Spain used the aera Hispanica from the fifth century well into the Middle Ages.

• Calendar era
• Computus

• Dates and Dating from the Catholic Encyclopedia