The Eagle of the Ninth was published in 1953 - Rosemary Sutcliff's first Roman Britain book. She hadn't realised that there was no archaeology at the time that supported the idea that Exeter had a Roman occupation, and was delighted to find out, later on, that 'traces of the Second Legion were being dug up all over the city'.
Snag is, it turns out now that a lot more excavating has been done that the Second Legion occupation of Exeter was in the first century, not the second, when Eagle of the Ninth is set. It looks like the Second Legion campaigned successfully in the Southwest, then left. By the time Marcus was supposed to be posted to Isca, they had moved elsewhere, leaving their huge legionary fortress on the Red Mount largely empty, and Isca Dumnoniorum was a city served by an aqueduct (although exactly how developed it was is not entirely clear, because of medieval ground clearances which have removed a lot of the Roman bits).
Fortunately, Sutcliff left an opening in this seemingly intractable wall of evidence, because she made Marcus and his troop auxiliaries, not regular legionaries. Auxiliaries are very poorly documented, and there seems no reason why the legionary fortress at Isca should not have been partially closed down, but still housing a few units of auxiliaries to keep an eye on things. Admittedly, that's not quite what Sutcliff described, but it's not far off. Then the various improvements in the buildings at Isca that Cassius made came along after Marcus's time, on the proceeds of the mining industry.
There is one small indication that life at Isca in the second century AD was not entirely peaceful. At some point, someone built a wall around the town - presumably, because there was someone who needed to be kept out. I've pushed the date of this a little earlier than is really likely - some of the sources suggest as late as 170, rather than as early as 140 (eleven years after the end of the book, when my story is set). But 140 doesn't seem to be considered impossible as a date, some sources suggested 130-150AD. So I decided that the wall around the town was put up by someone who knew about the Dumnonii chariot attack that Marcus stopped - Cassius. (He also put in the nice new surfaced road that was created at about the same time).
I needed Cassius to be a reasonably important individual, able to make decisions on issues like taxation and relations with local leaders, so I appointed him prefect. Prefect seems to be another of these slightly woolly titles that can have several meanings, but I think Cassius is a prefect fabri, with responsibility for engineers and building things, and his authority comes from the Governor of the province.
Exactly how much the Romans really used Dumnonian silver and tin is unclear. Dumnonia certainly did have extensive reserves of silver, tin, lead, and probably some gold, but Cornwall has been mined extensively and enthusiastically for several thousand years, so that it is as full of holes as a Swiss Cheese. It's hard to work out what the Romans might have done when pretty much every trace of their mining has been dug, scraped, and dynamited out of existence. I found a very handy thesis that argues in favour of the Romans having good reasons to mine in Dumnonia in the second century though.
In general, I found more evidence of Romans in the far West than I was expecting. I get the impression that there is a historical orthodoxy that No Roman Went West of Isca Dumnoniorum, and over the years this has become an orthodoxy with an increasingly long list of 'except fors'. But people writing general histories of Roman Britain still lop off the 'except fors' and move on to more exciting places with villas and cities. But it is perhaps worth considering that even now, there are only two cities West of Exeter, and both of them are tiny. I suspect if you looked at the material culture of 1950's Cornwall and compared it to, say, Sussex, you'd also find fewer 'high status' objects and buildings, without it being an enemy kingdom, as such.
The Brigantes conspiracy is real, although there's no evidence for a Dumnonian involvement. The Brigantes did revolt at around this time, attacking an otherwise obscure people called the 'Genounians' - which I have cavalierly overlapped with the Gabrantovice sept of the Brigantes tribe. The revolt, as Esca expected, was swiftly put down, and the Brigantes lost many of their lands. Poor Esca! The Antonine wall was built soon after, possibly as a result of the same campaign.
Belerion. None of the names for this area is at all clearly documented: it's very hard to work out what area or place is referred to, beyond 'Tamaris' which almost has to be somewhere along the river that is still called the Tamar. I decided that Gwynnarloedhis's people would call their land Belerion, taking the name from Diodorus Siculus, who is supposed to have visited Cornwall in 1BC. He said:
"The inhabitants of Britain who live on the promontory called Belerion are especially friendly to Strangers and have adopted a civilized way of life because of their interaction with traders and other people. It is they who work the tin..." This seems to be the only mention of the name 'Belerion' but it seemed way too good a name to waste. Obviously Marcus calls them all Dumnonii, but he's got it wrong. Tut.
Uxelis may be either Okehampton, or Launceston. I hope anyone reading this from either town will assume that when Vallaunus calls it an armpit, he clearly means the other town. And anyway, Vallaunus is clearly looking for the kind of excitement that no small rural town is likely to provide. Shocking.
The abandoned Roman fort where Cottia waits for Esca and Marcus exists, and was the original inspiration for this story. It's at Calstock, looking out over the river. Nobody knew about it until 2008, when an archaeologist who was looking for evidence of medieval silver mining suddenly realised that he'd made a once-in-a-lifetime discovery and found a fort that all the books say never existed.
It's enormous. When they did some digging there recently, they found a small broken Samianware cup. Clearly, this cup was one of a set with the Samianware bowl that Gwynnarloedhis presented to Marcus as her guest cup. Probably her grandmother's mother was given it by Vespasian, when Vespasian was a general of the Second Legion campaigning in Dumnonia/Belerion. :-D
Bre Skowl exists. It is also known as Kit Hill, the tallest hill on the west of the Tamar river between Dartmoor and Bodmin moor. The lower slopes are pretty much as described even today, but if you climb the hill like Esca, you will not find a hillfort on the top. The entire hill has been very thoroughly mined out over the intervening centuries.
It's the kind of place where you wander around and are not quite sure if the lump you just walked over is a Bronze Age burial mound, a nineteenth century mining spoilheap, or a Civil War fortlet deliberately constructed by an antiquarian general in the shape of a seventeenth century idea of a Saxon fortress (well, OK, there's only one of those. Probably.) Archaeologically it's a bit trashed. But it is surrounded by minor hillforts, and everyone in the area who is interested in the history is convinced there must have been one on top of it, because it just seems such an obvious place to put an important hill fort. So I did.
I did not make up Lucius Mancus, that very minor character. He existed, although I don't know anything else about him. At just about the right time, he scratched his name on a bit of pot which was later dug up in Plymouth, at the mouth of the river Tamar.
Novocrepidis isn’t a known Roman station, it’s a Latinisation of ‘Newquay’. The others are all real though.
The White Hare - there are odd hare/woman stories, about hares that turn into witches that turn into hares, or perhaps hares are the ghosts of women cheated in love, and sometimes they foretell storms at sea. They are associated with tin mining too. So far as I know, they are nothing like as old as the Roman occupation - but they seemed like something that might just be the end product of a tradition that started with a holy Hare-woman who was able to speak to the gods. But I have to admit that my reason for putting the White Hare in was just this Seth Lakeman song.