The portrayal of the reign of Justinian in Gibbon's History has not up to now received the attention it deserves, whether in terms of its presentation of one of the most brilliant periods covered in the work, or in relation to its function within the structure of the Decline and fall in its final form. Did Gibbon consider Justinian to be as ‘Roman’ as the emperor himself claimed to be? How did he make the narrative of the reconquest of the west fit his own account of the end of the western empire which precedes it? Where did Gibbon find his material, and how far was it possible for him to escape from the influence of Procopius, the contemporary historian who was at once Justinian's eulogist and his most savage critic? Many such questions suggest themselves, but while Gibbon's interest in Belisarius, Justinian's general and Procopius' hero, has been well noted, as has his fascination with the flamboyant empress Theodora, neither his use of Procopius as a main source nor the structural importance of this part of the Decline and fall, has been fully explored.

Two features of Gibbon's method in the History that have received a good deal of scholarly attention are highly relevant here too: these are his focus on certain individual characters – Julian the Apostate is one – and his use of certain ancient writers as major sources. Into the latter category fall two of his main sources and influences, Tacitus for the early Empire and Ammianus Marcellinus for the fourth century. When Gibbon can follow a full and detailed account he does so, while always interposing his own judgments based on other reading or critical perception.