The Notitia Dignitatum is a unique document of the Roman imperial chanceries. One of the very few surviving documents of Roman government, it details the administrative organisation of the eastern and westernempires, listing several thousand offices from the imperial court down to the provincial level. It is usually considered to be up to date for the Western empire in the 420s, and for the Eastern empire in 400s. However, no absolute date can be given, and there are omissions and problems.
There are several extant fifteenth and sixteenth-century copies (plus a colour-illuminated 1542 version). All the known and extant copies of this late Roman document are derived, either directly or indirectly, from a codexthat is known to have existed in the library of the cathedral chapter at Speyer in 1542 but which was lost before 1672 and cannot now be located. That book contained a collection of documents, of which the ‘Notitia’ was the last and largest document, occupying 164 pages. that brought together several previous documents of which one was of the 9th century. The heraldry in illuminated manuscripts of Notitiae is thought to copy or imitate no other examples than those from the lost Codex Spirensis. The most important copy of the Codex is that made for Pietro Donato (1436), illuminated by Peronet Lamy.
The Notitia presents four main problems, as regards the study of the Empire’s military establishment:
- The Notitia depicts the Roman army at the end of the 4th century. Therefore its development over the 4th century from the Principate structure is largely conjectural, due to the lack of other evidence.
- It was compiled at two different times. The Eastern section apparently dates from c395 AD; the Western from considerably later, c420. Furthermore, each section is probably not a contemporaneous “snapshot”, but relies on data stretching back as far as twenty years. The Eastern section may contain data from as early as 379, the start of the rule of Theodosius I. The Western section contains data from as early as c400: for example, it shows units deployed in Britain, which must date from before 410, when Roman troops were evacuated from the island. In consequence, there is substantial duplication, with the same unit often listed under different commands. It is impossible to ascertain whether these were detachments of the same unit in different places at the same time, or the same whole unit at different times. Also, it is likely that some units only existed on paper or contained just a skeleton personnel.
- The Notitia has many sections missing and lacunae (gaps) within sections. This is doubtless due to accumulated text losses and copying errors as it was repeatedly copied over the centuries: the earliest manuscript we possess today dates from the 15th century. The Notitia cannot therefore provide a comprehensive listing of all units in existence.
- The Notitia does not contain any personnel figures. Therefore, the size of individual units, and of the various commands, cannot be ascertained, as we have little other evidence of unit sizes at this time. In turn, this makes it impossible to assess accurately the overall size of the army. Depending on the strength of units, the late 4th century army may, at one extreme, have equalled the size of the 2nd century force (i.e. over 400,000 men); at the other extreme, it may have been far smaller. For example, the forces deployed in Britain c400 may have been just 18,000 against c55,000 in the 2nd century.