Type: Saxon Shore Fort, Fort
The first time the Roman name for the Portchester Saxon Shore Fort is mentioned is in the Notitia Dignitatum of the late-4th/early-5th centuries, where it appears as Portum Adurni, following the entry for Anderitum (Pevensey, East Sussex). The Portchester fort is last mentioned in the Ravenna Cosmology of the seventh century as Ardaoneon (R&C#43), between the unidentified station Armis and the entry for Navimago Regentium (Chichester, Sussex).
There are no inscriptions on stone recorded in the R.I.B. for Portchester. The only evidence we have which mentions the name of any of the garrison units at Portchester occurs in the Notitia Dignitatum, where the Portchester entry is the last listed "at the disposal of the Right Honorable Count of the Saxon shore in Britain". The full text is shown below.
|Praepositus numeri exploratorum, Portum Adurni|
"The commander of the Company of Scouts at Portus Adurni"
|(Notitia Dignitatum xxviii.21; 4th/5th C.)|
"Porchester (620 by 610 feet ; Fig. 12c) has gates to east and west, defended by projecting towers. The corners are angular and the bastions, which are U-shaped, are hollow. The walls are 10 feet thick and provided with bonding-courses; they stand in places over 20 feet high. The enclosed area is about 8 acres (V.C.H. Hants)." (Collingwood, p.53)
Plan of Portus Ardaoni with north at the top
(adapted from Collingwood, Fig.12.)
Ravenna Cosmography: Ardaoneon