Constantine the emperor


Constantine was Roman emperor from 306-337. He is credited as the first Roman emperor to have converted to Christianity, though the depth of his Christian conviction has been subject to debate. Through the Edict of Milan in 313 Christianity became one of the officially tolerated religions of the Empire. His mother Helena was believed to have discovered the True Cross. She was culted in England partly as a result of a tradition that she was the daughter of the British king of Colchester. Naturally, Constantine is presented in a favourable light by Eusebius, his biographer, but his reputation as pious Christian has been questioned, in particular during the Renaissance. One of his defenders was Caesar Baronius, whose biography of 1588 presents him as a model Christian ruler. Baronius was involved in the earliest editions of the Roman martyrology. Mart. O commemorates Constantine’s feast on 10th March, but this is not his usual feast day. Oengus’s source may have been Mart. T, but the non-Irish saints are missing for this day. He is not in Mart. G. nor in Mart. Usuard. The Roman martyrology mentions Constantine and Helen on 10th March in relation to a commemoration of St Macarius: ‘At Jerusalem, of St Macarius, bishop and confessor, at whose exhortation the holy places were purged by Constantine and Helena, and adorned with holy Basilicas’. Constantine died on May 22st. In the East he is usually commemorated, with Helen, on May 21st (ODS, 244).


He died on 22 May 337

Related Saints

Belongs to the group Constantine (ns)

Related Personal Names


Constantine (certain)

Feast days

Day of Year

May 21


This was the feast of Helen, Constantine's mother, but it was shared with Constantine himself. This was the date in the East. In the West the feast of Helen was August 18. Constantine died on 22 May.

Day of Year

March 10


Martyrology of Oengus the Culdee

Source code

Mart. O

Source title

Martyrology of Oengus the Culdee


Stokes, Whitley




Full title is Félire Óengusso Céli Dé, The Martyrology of Oengus the Culdee, critically edited from Ten Manuscripts, with a Preface, Translation, Notes and Indices.

Quote from source

Dorograd co hangliu Constantín cain coindlech, lassa frith éo ainglech, crann croiche in Choimmded. 'To the angels has been summoned Constantine the fair (and) luminous, by whom was found the angelical shaft, the tree of the Lord’s Cross.'


notes in Laud 610: Constantin .i. Consatin (sic) mac Elana lasa frith crux Christi. notes in RB505: Constantinn mac Helenae, de quo Hironimus dicit quod in principio uitae suae bonus, sed in fine malus fuit, quia in Arrianam perfidiam conuersus sic uitam finiuit.