With his friend McCabe, Márkus left Manchester for Oxford in 1950, where he joined the
Dominican Order at
Blackfriars, Oxford. It was at this time where he changed his name to Robert Austin Markus. Forbidden by his novice master from reading philosophy during his first year at Blackfriars, Markus was encouraged to read the scriptural commentaries of
Augustine. The study of Augustine would later become central to his scholarly work. In 1954, Markus left Blackfriars for
Birmingham, where he found work as a librarian. In 1955, Markus moved to
Liverpool, where he worked at the university library under the librarian and scholar Kenneth Povey. Povey encouraged Markus to continue his research and from 1958, Markus was lecturer, and later senior lecturer and reader, in the department of medieval history at the
University of Liverpool. At the time the department was headed by
Christopher N. L. Brooke. At the time Markus lectured on a number of subjects, including
Bede, and on ancient and medieval political thought. By 1960, Markus had become greatly interested in
Pope Gregory I, and was offered to supervise a Special Subject on him. Among the early students to follow Markus' special subject on Gregory the Great was
Ian Kershaw. In the 1960s, Markus befriended fellow historian
Peter Brown, with whom he established a close friendship. Along with Brown, Markus played a decisive role in establishing
Late Antiquity as a distinct period in European history. His reading of William Frend
The Donatist Church greatly influenced him. While Frend argued that the
Donatists represented the aspirations of the
Berbers of
North Africa, Markus agreed with Brown that they rather represented the pre-
Constantian uncentralised traditions of the African Church. In subsequent years, Markus studied the early history of Christianity as a force in the social and political history of
ancient Rome. His first monograph,
Saeculum: History and Society in the Theology of Saint Augustine (1970), saw Augustine as a dissenter from the triumphalism of the post-Constantinian Christianity. In his
Christianity in the Roman World (1974), Markus subjected the social and cultural history of Christianity to further study, and examined how it came to be the
state religion of the
Roman Empire. Markus argued that the growth of Christianity was largely achieved through its gradual incorporation of classical values, which made it more acceptable to Roman elites. In 1974, Markus was appointed Chair of Medieval History at the
University of Nottingham. By this time, he had established himself as leading authority on the history of the early Church. During his period at Nottingham, Markus contributed greatly making the Nottingham Department of Classics a leading institution in its field. He was President of the
Ecclesiastical History Society from 1978 to 1979. Markus took an early retirement from the University of Nottingham in 1982. He would later classify his early retirement as the best decision of his life apart from marrying his wife. He was elected a
Fellow of the British Academy in 1985. From 1986 to 1987 he was a visiting scholar at the
Institute for Advanced Study. He was Distinguished Visiting Professor at the
Catholic University of America in 1988. Although retiring from university duties apart from a few guest lectures, Markus continued researching and writing. His
The End of Ancient Christianity (1990) examined how Roman culture eroded from the time of Augustine to that of Pope Gregory the Great.
Wolf Liebeschuetz has described
The End of Ancient Christianity as Markus'
masterpiece. It was followed by
Gregory the Great and His World (1997). In these two studies Markus showed how the lives of these two figures intersected despite the continuing transformation of Christianity. From 1991 to 1995, Markus was President of the
International Association of Patristic Studies. He was Visiting Professor at
Notre Dame University in 1993. A
festschrift,
The Limits of Ancient Christianity: Essays on Late Antique Thought and Culture, was published in honor of Markus in 1999. Markus was appointed OBE in 2000. ==Death==