For the most part, mining in Britain was reasonably good, as the 33 known Roman iron mines on the island would suggest - it has even been suggested that around the time of the invasion, the Roman army used iron increasingly in the production of helmets and body armour from around this time. Tin was also to be found, especially in Cornwall, and this was exploited by the Romans to make bronze and pewter, both important alloys in the ancient world. However only one gold mine has been found, at Dolaucothi in Wales, and due to fierce resistance in Wales it wasn’t until 78 AD that mining could have started there. On the other hand, Tacitus said that ‘Britain bears gold and silver and other metals, the reward of victory' in the Agricola, written around 90AD, indicating that gold mining in Britain developed quite quickly after that. The most important metal mined in Britain was lead, since the pipes and aqueducts which supplied Rome were made from this. Pliny the Elder, a famous Roman naturalist, wrote that lead in Britain actually threatened Spanish mining, since lead was:
‘…extracted more laboriously in Spain and through the whole of Gaul, but in Britain, (it is found) so broadly in the top layer
that a law has been passed freely, that there should not be more (extracted) than a fixed limit’
Lead mining in Britain actually replaced Spanish mining in 70AD, and I learnt at Latin camp that tests carried out at Herculaneum have shown the lining of the public baths to be made out of lead from Britain. The short space of time between the conquest in 43AD and the eruption of Vesuvius in 79AD indicates that lead was indeed found in very great quantities on the island. Equally important was silver which could be extracted from lead ore - most Roman coins were minted in silver, and as a result it formed the basis of the economy. Consequently, mining in Britain is supportive of the interpretation of a successful invasion.
However metals weren’t the only resource of importance in Britain. Other exports such as dogs, duffle coats and pearls were acquired through the invasion. Unfortunately the archaeological evidence for these is lacking, since unlike mining they leave no traces behind, and so it is to the literary remains that we must turn. British hunting dogs were highly valued in Rome before the invasion, as shown by Strabo’s description of the island’s resources, and this continued to be the case, since the late Roman poet Claudian described dogs from the island as:
‘Britons that can break the great necks of bulls’
‘The ocean produces pearl, but dark and purplish. Some think that the gatherers lack skill, for in the Red Sea they are torn
from the rocks alive and breathing, in Britain they are gathered just as they are thrown up. I would more easily believe the
nature of the pearl to be lacking than our own greed’
Tacitus was a historian and the son in law of Agricola, the governor of Britain - while he'd have been well informed, he'd also have been strongly biased towards the Romans and more likely to conclude that the pearls, rather than his countrymen, were disappointing. Claudius’ advisors may have been misled about the value of pearls from British oysters, and certainly they weren’t anywhere near the quality that the Romans sought for use in jewellery. As a result, it is highly unlikely that they would have been successful in making much profit.
‘...at present, more revenue is derived from the duty on their commerce than the tribute could bring in, if we
deduct the expense involved in the maintenance of an army for the purposes of guarding the island and collecting the tribute’
It is important to consider the situation when Strabo was writing. The unrest which disrupted trade between Britain and Rome only surfaced in Claudius’ reign, a fair while after Strabo’s Geography was probably written. As a result it is plausible that during Claudius' time, trade had been damaged enough that an invasion would have been more profitable than not (although unfortunately no records remain on this matter, and so we can only speculate). On the other hand, it was initially thought that Britain would only require one legion and some auxiliary cavalry as a garrison; in fact three legions were stationed in Britain along with a number of auxiliary troops, suggesting that the cost of the invasion was significantly more than Strabo predicted (something I will return to next time). So perhaps the tax from Roman Britain was likely less profitable than the custom duties collected beforehand.
Overall, the resources from Britain present a mixed picture as to how far the invasion was a success. Mining on the island appears to have been very profitable, and evidence would suggest that the Romans lost no time in this area. The abundance of certain metals, which initially threatened Spanish mines, later became more significant later as resources in Spain ran out. In addition, British hunting dogs continued to be in demand until the collapse of the Empire. However pearls from British oysters were of fairly low quality, and other exports such as duffle coats, while useful, can’t really be used to claim the invasion was a success. Equally, the tax from Britain was nothing exceptional, and the conquest may in fact have meant a decrease in Rome’s revenue, suggesting that the invasion wasn’t profitable in this respect. Unfortunately, there is little evidence available to me to assess whether the invasion of Britain was profitable, making it difficult to come to any conclusive conclusion. Either way, resources were not especially important among Claudius’ initial aims, and so while it is ironic that British metals proved to be valuable before long, it is harder to consider the conquest a success on this basis.
Hopefully the length of this post hasn't scared everyone away (it'll probably be the longest in the series), if you managed to make your way through all that then you certainly have my gratitude! In the next part of this series I'll be looking at whether the conquest of Britain was an easy victory for Claudius, but before then, I plan on doing a post about the Oxford Classics interview (something I've meant to do for quite a while), so stay tuned for that. Thanks for reading!