The
Era of the Martyrs (
Latin:
anno martyrum or AM), also known as the
Diocletian era (Latin:
anno Diocletiani), is a method of numbering years used by the
Church of Alexandria beginning in the 4th century
anno Domini and by the
Coptic Orthodox Church of Alexandria from the 5th century to the present. 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. Diocletian began his reign 20 November 284 during the Alexandrian year that began on 1 Thoth, the Egyptian New Year, or 29 August 284, so that date was used as the
epoch: year one of the Diocletian era began on that date. This era was used to number the year in
Easter tables produced by the Church of Alexandria.