For the earliest period of Exeter, Geoffrey of Monmouth supplies much information, which has been greatly borne out by subsequent researches. He considered that Exeter was a city of the Britons some time before the Romans elected to establish their camp. The British named it indifferently Cær-Wisc (city of the water), or Cær Rydh (the red city), from the coloured nature of the soil. When captured by the Romans they made it a stipendiary town. They called it Isca, to which was added Danmoniorum, to avoid confusion with the other Isca, a Latinised name given also to a town on the river (now Usk) in Monmouthshire. Many proofs of Roman occupation have turned up in the shape of numerous coins and other relics.
The year 1778 was especially notable for the excavations which brought to light many important objects. Small statuettes of Mercury, Mars, Ceres, and Apollo, evidently the household gods of the Romans, together with urns, tiles, and tessellated pavements, were unearthed. Exeter at one time went by the name of Augusta, which was due to its having been occupied by the Second Augustan Legion, whose commander, Vespasian, included the city under his conquest Britannia Prima. The same legion, during the period 47 to 52, had also a permanent station at Isca Silurum, as Cærleon-on-the-Usk in Monmouth was called. But as Vespasian continued the conquest, 69 to 79, it seems fair to surmise that the Second Legion of Augusta was advanced or a portion sent from Isca Silurum to garrison Isca Danmoniorum, the present Exeter.
For a considerable time it was the capital of the West Saxon kingdom. It was probably during the Saxon occupation that the city changed its name to Excestre, which would easily be contracted into that of Exeter. In violation of a compact made with Alfred, who was a Saxon monarch, the Danes seized the city. They were, however, compelled to evacuate it, together with the surrender of all their prisoners within the West Saxon territory, by Alfred, in 877. This monarch was again called upon in 894 to relieve the Saxons from their Danish oppressors. The next century witnessed a marked improvement in the prosperity of the city. It had from quite an early period been distinguished for its numerous monastic institutions, so much so that it was said to have been called "Monk Town" by Britons in Cornwall and the heathen Saxons. They were pleased to deride it thus, but when Athelstan came he clearly made them understand that it was no happy state to be without the pale of the Church. He so thoroughly instilled into them the necessity of imbibing the principles of religion that those who were unwilling to become converts were expelled.