I have seen many people, mostly in the comments of news articles, compare the Roman occupation of Britain with later colonial efforts by Europeans. They portray the Romans as brutal colonisers and oppressors, destroyers of the local way of life, who left a battered country in their wake.
For example, when one comment mentions the ‘dark ages’, another replies: “it’s almost as if colonialism is traumatising to a country’s growth and social structures oh my god...”
Another: “That's what happens when Colonialism leaves it's oppressive foreign religions behind.”
A third: “Which is what happens when an invading power utterly massacres all trace of the native cultural and spiritual leadership of a people, renders the populace forcibly into its own culture stamp, or else enslaves them wholesale, and then summarily implodes under the weight of its own tyrannical comeuppance. For modern example, see Iraq post Operation Desert Storm, and the rise of ISIL.”
Now my first and admittedly uninformed instinct is to think that this reeks of an attempt to force a newer narrative onto older events that simply cannot be described that way. A false equivalency, trying to fit the Roman square peg into the colonist round hole. But then, as I mentioned, I don’t know that much about the history.
My question then is: can Roman occupation of Britain be effectively described as colonial, or colonial in character? Secondly, would it be fair to argue that post-Roman Britain experienced post-colonial trauma?
Forgive me if this long winded question is unclear.
"Can the Roman occupation of Britain be effectively described as colonial?"
I'm going to be going off a basic modern definition of colonialism, "the policy or practice of acquiring full or partial political control over another country, occupying it with settlers, and exploiting it economically."
Did the Romans aquire full or partial political control? Yes, absolutely. Did they occupy it with settlers? A bit, but not much, more on that in a moment. Did they exploit it economically? The tax rate was quite high, but generally not.
Our main source on the Roman occupation of Britain is Tacitus, who was a prominant senator with an interest in tribal peoples and the son-in-law of Agricola, the governor of Britain from 77-85 AD. Cassius Dio, a 3rd century Greek senator, gives a little bit of additional information but not much. There is also plenty of archeology from the Romans, but not from the natives as they did not build things out of concrete.
Rome did establish some colonies in Britain (London, Leister, St. Albans, Winchester etc.), and sought to extract revenue from it, and in doing so meets the modern definition of colonialism, but they did not attempt to supplant the locals like the US did to the Native Americans, or the British did to the natives of Australia and New Zealand. Places like Londinium were defnitely colonies, but others such as Newcastle were accidents. Newcastle was a base of operations for the Roman army and home to a major fort (hence it's name), and a town of about 2000 people sprang up around it. The Romans didn't build it; it would have been very stupid to build a town that close to the frontier. The population of these towns were only a few thousand each and the locals would have overwhelmingly outnumbered them in these accidental towns (not counting the soldiers that periodically occupied the fort), almost all of which emerged near military bases. Planned settlements like Bath or London are more difficult, but it seems they were designed to accommodate a mixed population since the temples combined native and Greco-Roman gods.
As for economic exploitation, there was not the kind of rampant resource exploitation synonymous with European colonialism in Africa. Although Britannia was profitable - Tacitus and Dio both claim it had a high tax rate - money was not the main goal of conquering Britain. Both Caesar and Claudius had invaded Britain because of it's near mythical status in Rome. When Caesar invaded, some Romans did not even believe Britain was real. When Claudius launched his far more successful invasion, it was because he was a new emperor and needed to prove his worth - topping the deeds of Caesar went a long way to achieving that. There was some mineral wealth to be had; Pliny the Elder tells us that Britain was known for lead, tin and amber, but not so much that it would be worth sending armies to conquer it when it could simply be bought (as it had been for centuries prior). Since the basics are there but the brutality is not, it may therefore be fair to describe Roman policy in Britain as 'colonialism-lite'. It does however have a proper name; romanisation.
The policy of Rome toward Britain is not generally referred to as colonial. As you rightly identify, colonialism is an anachronistic term when applied to Romans. What the Romans were doing is romanisation - trying to make the locals more culturally Roman. Although the point of it is much the same as colonialism, the method is rather different. Colonialism is very hostile; peoples are subjugated by force and often killed and enslaved, romanisation is more subtle and deliberately generous so as to win over conquered people without forcing them to do anything. The Romans were fully capable of colonialism in the modern manner; when Caesar took Gaul he massacred or enslaved entire peoples, and slaves were sent to work the mines of Iberia (modern Spain and Portugal), which was a grim existence. Furthermore, Domitian subjugated Dacia for its gold and silver mines, a thoroughly exploitative endeavour that would make Cecil Rhodes proud. Britain just didn't have that kind of mineral wealth. Romanisation was deliberately milder, relying on encouragement rather than force. Tacitus, in his typical cynical wit, puts it quite well:
"Agricola gave encouragement and public aid to the building of temples, courts of justice and new houses, praising the energetic, and reprimanding the idle. Honourable rivalry got things done rather than compulsion. He likewise provided a liberal education for the sons of the chiefs, and encouraged the learning of Latin, which the Britons have a more natural affinity for than the Gauls, who try harder. A liking sprang up for our style of dress, and the toga became fashionable. Step by step they were led to things which dispose to vice: the lounge, the bath, the elegant banquet. In thier ignorance they called this civilisation, when it was part of their enslavement."
The Romans introduced Roman law, integrated native gods into the Roman pantheon (for example, the British god Sulis was combined with Minerva; in the town of Bath there is a temple to Sulis-Minerva), taught people Latin and built new towns, baths and threw parties. If you were a Briton, then Agricola's campaign of romanisation meant better hygiene, more infrastructure, more trade, better tools, a more varied diet etc. The goal was not to subjugate the peoples of Britain, but to win them over. To call Roman policy 'colonial' does this aspect of Agricola's policy a disservice.
"Would it be fair to argue that post-Roman Britain experienced post-colonial trauma?"
In a way, yes. In 410 Rome issued the Pragmatic Sanction, a document that officialy removed Britain from the Roman Empire. The army left, though a lot of Romans stayed behind. We don't know enough about sub-Roman Britain (the period after 410 but before the Anglo-Saxons took over) to say how things went for sure, but it was clearly a time of economic disaster. Archeological evidence shows abandonment of many cities, most notably Londinium, which would not be occupied again until Alfred the Great. Most villas were abandoned at this time, further indicating a serious loss of wealth. Without the money and engineering expertise of Rome, infrastructure such as baths, roads, walls, and aquaducts could not be maintained. Cities became dangerous as they crumbled; archeological evidence suggests that many city-dwellers simply made a new town down the road, as happened with the residents of Londinium, who created the imaginatively named town of Londonwick about 2 miles down the river Thames.
They also struggled on a political level as well as an economic one. Gildas, a bishop writing around 520 AD, gives a depressing account of what happened in a sermon called 'The Ruin of Britain'. Essentially, without the Roman army guarding the north, the Picts and Caledonians raided south. The Romans and British leaders got together and offered land to the Angles, Jutes and Saxons - Germanic tribes with small settlements in the south-east - if they would help fight off these raids. As time went on the Angles and Saxons demanded more and more in exchange for continued service and the country descended into war between the Anglo-Saxons and the locals led by Ambrosius Aurelianus, who was apparently the grandson of a Roman governor (this suggests that despite the Pragmatic Sanction, Britain was still under Roman style administration). We have no idea at all where the Jutes were in all this.
So in short, the economy tanked, infrastructure broke and leadership problems were rife. This is also what happened in many post-colonial nations such as Zimbabwe, Congo, Sudan etc, so it would be fair to say that sub-Roman Britain suffered a similar phenomenon.