The notation Old Style or (OS) is sometimes used to indicate a date in the Julian Calendar (which is used by churches on the "Old Calendar"). The notation New Style or (NS), indicates a date in the Revised Julian calendar (which is used by churches on the "New Calendar").
Martyr Eusebius lived during the reign of Diocletian (284-305 AD) and was a courtier of the Senate. He converted to Christianity during the witness of Bishop Theopemptus in Rome († 5 January), when he saw the spiritual prowess of that Saint during his tortures, and the miracles that he performed. Because he became a Christian he was arrested and led before the Emperor, where he confessed his faith in Christ. He was martyred with horrible tortures and was partitioned with an axe in the year 298 AD.
Fabian succeeded St Antherus as Pope of Rome in 236 and was martyred in 250 under Decius. St Cyprian described him as an 'incomparable man' and added that the glory of his death matched the purity and goodness of his life.
According to his Life, he was an officer in the imperial army and a favourite of Diocletian. Nevertheless, when he was discovered to be Orthodox no mercy was shown him. Tied to a tree, his body was made a target for Roman archers and he was finally martyred with clubs. His church is one of the seven main churches in Rome.
Born in Connaught in Ireland, he founded several monasteries. His name is connected with Fobhar (Fore) in Westmeath. Ecclefechan and St Vigean's near Arbroath in Scotland are also called after him.
The Autonomous Orthodox Metropolia of Western Europe and the Americas (ROCOR). St. Hilarion Calendar of Saints for the year of our Lord 2004. St. Hilarion Press (Austin, TX). p.9.
The Autonomous Orthodox Metropolia of Western Europe and the Americas (ROCOR). St. Hilarion Calendar of Saints for the year of our Lord 2004. St. Hilarion Press (Austin, TX). p.9.
January 20. Latin Saints of the Orthodox Patriarchate of Rome.
The Roman Martyrology. Transl. by the Archbishop of Baltimore. Last Edition, According to the Copy Printed at Rome in 1914. Revised Edition, with the Imprimatur of His Eminence Cardinal Gibbons. Baltimore: John Murphy Company, 1916. pp.20–21.
(in Greek) Συναξαριστής. 20 Ιανουαρίου. ECCLESIA.GR. (H ΕΚΚΛΗΣΙΑ ΤΗΣ ΕΛΛΑΔΟΣ).
Russian Sources
(in Russian)2 февраля (20 января). Православная Энциклопедия под редакцией Патриарха Московского и всея Руси Кирилла (электронная версия). (Orthodox Encyclopedia - Pravenc.ru).