Historical records beyond the initial invasion are sparse, although many Roman historians mention the province in passing. Most of the knowledge of the period stems from archaeological investigations and especially epigraphic evidence.
The first direct Roman contact came when the Roman general and future dictator, Julius Caesar, made two expeditions to Britain in 55 and 54 BC as an offshoot of his conquest of Gaul, believing the Britons had been helping the Gallic resistance. The first expedition, more a reconnaissance than a full invasion, gained a foothold on the coast of Kent but, undermined by storm damage to the ships and a lack of cavalry, was unable to advance further. The expedition was a military failure but a political success: the Roman Senate declared a 20-day public holiday in Rome in honour of this unprecedented achievement.
In his second invasion Caesar took with him a substantially larger force and proceeded to coerce or invite many of the native tribes to pay tribute and give hostages in return for peace. A friendly local king, Mandubracius, was installed, and his rival, Cassivellaunus, was brought to terms. Hostages were taken, but historians disagree over whether the tribute agreed was paid by the Britons after Caesar's return to Gaul.
Caesar had conquered no territory but had established clients on the island and brought Britain into Rome's sphere of political influence. Augustus planned invasions in 34, 27 and 25 BC, but circumstances were never favourable, and the relationship between Britain and Rome settled into one of diplomacy and trade. Strabo, writing late in Augustus's reign, claims that taxes on trade brought in more annual revenue than any conquest could. Likewise, archaeology shows an increase in imported luxury goods in southeastern Britain. Strabo also mentions British kings who sent embassies to Augustus, and Augustus' own Res Gestae refers to two British kings he received as refugees. When some of Tiberius's ships were carried to Britain in a storm during his campaigns in Germany in AD 16, they were sent back by local rulers, telling tall tales of monsters.
Rome appears to have encouraged a balance of power in southern Britain, supporting two powerful kingdoms: the Catuvellauni, ruled by the descendants of Tasciovanus, and the Atrebates, ruled by the descendants of Commius. This policy was followed until AD 39 or 40, when Caligula received an exiled member of the Catuvellaunian dynasty and staged an invasion of Britain that collapsed in farcical circumstances before it left Gaul. When Claudius successfully invaded in 43, it was in aid of another fugitive British ruler, this time Verica of the Atrebates.
The invasion was delayed by a mutiny of the troops, who were eventually persuaded by an imperial freedman to overcome their fear of crossing the Ocean and campaigning beyond the limits of the known world. They sailed in three divisions, and probably landed at Richborough in Kent, although some suggest that at least part of the invasion force landed on the south coast, in the Fishbourne area of West Sussex.
The Romans defeated the Catuvellauni and their allies in two battles: the first, assuming a Richborough landing, in a battle on the river Medway, the second on the Thames. One of the Catuvellaunian leaders, Togodumnus, was killed, but his brother Caratacus survived to continue resistance elsewhere. Plautius halted at the Thames and sent for Claudius, who arrived with reinforcements, including artillery and elephants, for the final march to the Catuvellaunian capital, Camulodunum (Colchester). The future emperor Vespasian subdued the southwest, Cogidubnus was set up as a friendly king of several territories, and treaties were made with tribes outside the area under direct Roman control.
After capturing the south of the island, the Romans turned their attention to what is now Wales. The Silures, Ordovices and Deceangli remained implacably opposed to the invaders and for the first few decades were the focus of Roman military attention, despite occasional minor revolts among Roman allies like the Brigantes and the Iceni. The Silures were led by Caratacus, and he carried out an effective guerrilla campaign against Governor Publius Ostorius Scapula. Finally, in 51, Ostorius lured Caratacus into a set-piece battle and defeated him. The British leader sought refuge among the Brigantes, but their queen, Cartimandua, proved her loyalty by surrendering him to the Romans. He was brought as a captive to Rome, where a dignified speech he made during Claudius's triumph persuaded the emperor to spare his life. However, the Silures were still not pacified, and Cartimandua's ex-husband Venutius replaced Caratacus as the most prominent leader of British resistance.
In 60-61, while Governor Gaius Suetonius Paulinus was campaigning in Wales, the southeast of Britain rose in revolt under Boudica, widow of the recently-deceased king of the Iceni, Prasutagus, provoked by the seizure of the tribe's lands and the brutal treatment of the queen and her daughters. Prasutagus had left a will leaving half his kingdom to Nero in the hope that the rest would be left untouched. He was wrong. The Iceni, joined by the Trinovantes, destroyed the Roman colony at Camulodunum and routed the part of the IX legion that was sent to relieve it. Suetonius Paulinus rode to London, the rebels' next target, but concluded it could not be defended. Abandoned, it was destroyed, as was Verulamium (St Albans). Between seventy and eighty thousand people are said to have been killed in the three cities. But Suetonius regrouped with two of the three legions still available to him, chose a battlefield, and, despite being heavily outnumbered, defeated the rebels in the Battle of Watling Street. Boudica died not long afterwards, by self-administered poison or by illness. The revolt had almost persuaded Nero to withdraw from Britain altogether.
There was further turmoil in 69, the "year of four emperors". As civil war raged in Rome, weak governors were unable to control the legions in Britain, and Venutius of the Brigantes seized his chance. The Romans had previously defended Cartimandua against him, but this time were unable to. Cartimandua was evacuated, and Venutius was left in control of the north of the country. After Vespasian secured the empire, his first two appointments as governor, Quintus Petillius Cerialis and Sextus Julius Frontinus, took on the task of subduing the Brigantes and Silures respectively. Frontinus extended Roman rule to all of South Wales, and initiated exploitation of the mineral resources, such as the gold mines at Dolaucothi.
In the following years, the Romans conquered more of the island, increasing the size of Roman Britain. Governor Gnaeus Julius Agricola, father-in-law to the historian Tacitus, conquered the Ordovices in 78. With XX Valeria Victrix, Agricola defeated the Caledonians in 84 at the Battle of Mons Graupius, in what is today northern Scotland. This marked the high tide mark of Roman territory in Britain; shortly after his victory, Agricola was recalled from Britain back to Rome, and the Romans retired to a more defensible line along the Forth-Clyde isthmus, freeing soldiers badly needed along other frontiers.
For much of the history of Roman Britain, a large number of soldiers were garrisoned on the island. This required that the emperor station a trusted senior man as governor of the province. As a side-effect of this, many future emperors served as governors or legates in this province, including Vespasian, Pertinax, and Gordian I.
Around 105, however, a serious setback appears to have happened at the hands of the tribes of the Picts of Albu; several Roman forts were destroyed by fire with human remains and damaged armour at Trimontium (at modern Newstead, in southeastern-most Scotland) indicating hostilities at least at that site. There is also circumstantial evidence that auxiliary reinforcements were sent from Germany, and an unnamed British war from the period is mentioned on the gravestone of a tribune on Cyrene. However, Trajan's Dacian Wars may have led to troop reductions in the area or even total withdrawal followed by slighting of the forts by the Picts rather than an unrecorded military defeat. The Romans were also in the habit of destroying their own forts during an orderly withdrawal, in order to deny resources to an enemy. In either case, the frontier probably moved south to the line of the Stanegate at the Solway-Tyne isthmus around this time.
A new crisis occurred at the beginning of Hadrian's reign (117), a rising in the north which was suppressed by Quintus Pompeius Falco. When Hadrian reached Britannia on his famous tour of the Roman provinces around 120, he directed an extensive defensive wall, known to posterity as Hadrian's Wall, to be built close to the line of the Stanegate frontier. Hadrian appointed Aulus Platorius Nepos as governor to undertake this work who brought VI Victrix with him from Lower Germany. Legio VI replaced the famous IX Hispana, whose disappearance has been much discussed. Archaeology indicates considerable instability in Scotland during the first half of the second century, and the shifting frontier at this time should be seen in this context.
In the reign of Antoninus Pius (138-161) the Hadrianic border was briefly extended north to the Forth-Clyde isthmus, where the Antonine Wall was built around 142 following the military re-occupation of the Scottish lowlands by a new governor, Quintus Lollius Urbicus. This northward extension of the empire was probably the result of attacks, maybe by the Selgovae of southeast Scotland, on the Roman buffer state of the Votadini who lived north of the Hadrianic frontier.
The first Antonine occupation of Scotland ended as a result of a further crisis in 155-157, when the Brigantes revolted. With limited options to despatch reinforcements, the Romans moved their troops south, and this rising was suppressed by Governor Cnaeus Julius Verus. Within a year the Antonine Wall was reoccupied, but by 163 or 164 it was abandoned. The second occupation was probably connected with Antonius' undertakings to protect the Votadini or his pride in enlarging the empire, since the retreat to the Hadrianic frontier occurred not long after his death when a more objective strategic assessment of the benefits of the Antonine Wall could be made. The Romans did not entirely withdraw from Scotland at this time, however; the large fort at Newstead was maintained along with seven smaller outposts until at least 180.
During the twenty year period following the reversion of the frontier to Hadrian's Wall, Rome was concerned with continental issues, primarily problems in the Danube provinces. Increasing numbers of hoards of buried coins in Britain at this time indicate that peace was not entirely achieved. Sufficient Roman silver found in Scotland suggests more than ordinary trade, and it is likely that the Romans were boosting treaty agreements by paying tribute to their implacable enemies, the Picts.
In 175, a large force of Sarmatian cavalry, consisting of 5,500 men, arrived in Britannia, probably to reinforce troops fighting unrecorded uprisings. In 180, Hadrian's Wall was breached by the Picts and the commanding officer or governor was killed there in what Dio Cassius described as the most serious war of the reign of Commodus. Ulpius Marcellus was sent as replacement governor and by 184 he had won a new peace only to be faced with a mutiny from his own troops. Unhappy with Marcellus' strictness, they tried to elect a legate named Priscus as usurper emperor; he refused, but Marcellus was lucky to leave the province alive. The Roman army in Britannia continued its insubordination; they sent a delegation of 1,500 to Rome to demand the execution of Tigidius Perennis, a Praetorian Prefect who they felt had earlier wronged them by posting lowly equites to legate ranks in Britannia. Commodus met the party outside Rome and agreed to have Perennis killed, but this only made them feel more secure in their mutiny.
The future emperor Pertinax was sent to Britannia to restore order and was initially successful in regaining control. A riot broke out amongst the troops however, in which Pertinax was attacked and left for dead, and he asked to be recalled to Rome, briefly succeeding Commodus in 192.
Albinus crossed to Gaul in 195 where the provinces were also sympathetic to him and set up at Lugdunum. Severus arrived in February 196, and the ensuing battle was decisive. Although Albinus came close to victory, Severus' reinforcements won the day, and the British governor committed suicide. Severus soon purged Albinus' sympathisers and perhaps confiscated large tracts of land in Britain as punishment.
Albinus demonstrated the two major political problems posed by Roman Britain. First, in order to maintain its security it had three legions stationed there. These would provide an ambitious man with weak loyalties a powerful base for rebellion, as it had for Albinus. Second, deploying the legions elsewhere would strip the island of its garrison, with the result that Britain was defenceless to invaders.
Traditionally, the view has been that northern Britain descended into anarchy during Albinus' absence. Cassius Dio records that the new Governor Virius Lupus was obliged to buy peace from the fractious northern tribe known as the Maeatae. A succession of militarily distinguished governors appointed to the province suggests these enemies of Rome were providing a difficult challenge, and Lucius Alfenus Senecio's report back to Rome in 207 described barbarians "rebelling, over-running the land, taking loot and creating destruction". In order to rebel, one must be a subject, and the Maeatae clearly did not consider themselves such. Alfenus requested either reinforcements or an Imperial expedition, and Severus chose the latter option, despite being 62 years old.
Archaeological evidence shows that Alfenus had been rebuilding the defences of Hadrian's Wall and the forts beyond it, and Severus' arrival in Britain prompted the enemy tribes to immediately sue for peace. The emperor had not come all that way to leave without a victory however, and it is likely that he wished to provide his teenage sons Caracalla and Geta with first hand experience of controlling a hostile barbarian land.
An expedition led by Severus and probably numbering around 20,000 troops moved north in 208 or 209, crossing the wall and passing through eastern Scotland in a route similar to that used by Agricola. Harried by punishing guerrilla raids by the northern tribes and slowed by an unforgiving terrain, Severus was unable to meet the Caledonians on a battlefield. The emperor's forces pushed northwards as far as the River Tay, but little appears to have been achieved by the invasion, as peace treaties were signed with the Caledonians. By 210, Severus had returned to York with the frontier set at Hadrian's Wall and assumed the title Britannicus. The title would mean little with regard to the unconquered north, which (with Rome's power still stopping at the Wall) clearly remained outwith the authority of the Empire. And almost immediately another northern tribe, the Maeatae, again went to war. Caracella left with a punitive expedition, but by the next year his ailing father had died and he and his brother left the province to press their claim for the throne.
As one of his last acts, Septimius Severus tried to solve the problem of powerful and rebellious governors in Britain by dividing the existing province into Upper Britain and Lower Britain. Although this kept the potential for rebellion in check for almost a century, it was not permanent. Historical sources provide little information on the following decades, a period often called the Long Peace. Even so the number of hoards found in the period rises, suggesting unrest. A string of forts were built along the coast of southern Britain to control piracy; over the next hundred years they expanded in number, becoming the Saxon Shore Forts.
During the middle of the third century the Roman Empire was convulsed by barbarian invasions, rebellions and new imperial pretenders. Britannia apparently avoided these troubles, although increasing inflation had its economic effect. In 259, a so-called Gallic Empire was established when Postumus rebelled against Gallienus. Britannia was part of this until 274, when Aurelian reunited the empire.
In the late 270s a half-Brythonic usurper named Bononus rebelled to avoid the repercussions of letting his fleet be burnt by barbarians at Cologne. He was quickly crushed by Probus, but soon afterwards an unnamed governor in Britannia also attempted an uprising. Irregular troops of Vandals and Burgundians were sent across the Channel by Probus to put down the uprising, perhaps in 278.
The last of the string of rebellions to affect Britannia was that of Carausius and his successor Allectus. Carausius was a naval commander, probably in the English Channel. He was accused of keeping pirate booty for himself, and his execution was ordered by the Emperor Maximian. In 286, he set himself up as emperor in Britain and northern Gaul and remained in power whilst Maximian dealt with uprisings elsewhere. In 288, an invasion failed to unseat the usurper. An uneasy peace ensued, during which Carausius issued coins proclaiming his legitimacy and inviting official recognition.
In 293, Constantius Chlorus launched a second offensive, besieging the rebel's port at Boulogne and cutting it off from naval assistance. After the town fell, Constantius tackled Carausius' Frankish allies. Subsequently the usurper was murdered by his treasurer, Allectus. Allectus' brief reign was brought to an end when Julius Asclepiodotus landed near Southampton and defeated him in a land battle.
Constantius arrived in London to receive the victory and chose to divide the province further, into four provinces:
These four provinces were part of Diocletian's Tetrarchy reform in 293: Britannia became one of the four dioceses—governed by a vicarius—of the prætorian prefecture Galliae ('the Gauls', also comprising the provinces of Gaul, Germania and Hispania), after the abolition of the imperial tetrarchs under the Western Emperor (in Rome itself, later Ravenna).
Constantius remained in Britain for the rest of the time he was part of the Tetrarchy, dying on July 25 306. His son, Constantine I, had managed to be by his side at that moment and assumed his duties in Britain. Unlike the earlier usurper Albinus, he was able to successfully use his base in Britain as a starting point on his march to the imperial throne.
For a few years, the British provinces were loyal to the usurper Magnentius, who succeeded Constans following his death. Following the defeat and death of Magnentius in the Battle of Mons Seleucus in 353, Constantius II dispatched his chief imperial notary Paul "Catena" to Britain to hunt down Magnentius' supporters. Paul's investigations deteriorated into a witch hunt, which forced the vicarius Flavius Martinus to intervene. When Paul instead suspected Martinus of treason, the vicarius found himself forced to physically attack Paul with a sword with the aim of assassinating him, but at the end he committed suicide.
In the 4th century, there were increasing attacks from the Saxons in the east and the Irish in the west. A series of forts was built, starting around 280, to defend the coasts, but these preparations were not enough when a general assault of Saxons, Irish and Attacotti, combined with apparent dissension in the garrison on Hadrian's Wall, left Roman Britain prostrate in 367. This crisis, sometimes called the Great Conspiracy, was settled by Count Theodosius with a string of military and civil reforms.
Another usurper, Magnus Maximus, raised the standard of revolt in Segontium in 383 and crossed the Channel. Maximus held much of the western empire and fought a successful campaign against the Picts and Scots around 384. His continental exploits required troops from Britain, and it appears that forts at Chester and elsewhere were abandoned at this period, triggering raids and settlement in north Wales by the Irish. His rule was ended in 388, but not all of the British troops may have returned: the Empire's military resources were struggling after the catastrophic Battle of Adrianople in 378. Around 396, there were increasing barbarian incursions in Britain, and an expedition, possibly led by Stilicho, brought naval action against the raiders. It seems peace was restored by 399, although it is likely that no further garrisoning was ordered, and indeed by 401 more troops were withdrawn to assist in the war against Alaric I.
The traditional view of historians, informed by the work of Michael Rostovtzeff, was of a widespread economic decline at the beginning of the fifth century. However, consistent archaeological evidence has told another story, and the accepted view is undergoing re-evaluation. The destruction of many sites is now believed to be much later than had formerly been thought. Many buildings changed use but were not destroyed. There were growing barbarian attacks, but these were focused on vulnerable rural settlements rather than towns. Some villas such as Great Casterton in Rutland and Hucclecote in Gloucestershire had new mosaic floors laid around this time, suggesting that economic problems may have been limited and patchy, although many suffered some decay before being abandoned in the fifth century; the story of Saint Patrick indicates that villas were still occupied until at least 430. New buildings were still going up in this period in Verulamium and Cirencester. Some urban centres, for example Canterbury, Cirencester, Wroxeter, Winchester and Gloucester, remained active during the fifth and sixth centuries, surrounded by large farming estates.
Urban life had generally grown less intense by the fourth quarter of the fourth century, and coins minted between 378 and 388 are very rare, indicating a likely combination of economic decline, diminishing numbers of troops, and problems with the payment of soldiers and officials. Coinage circulation increased during the 390s, although it never attained the levels of earlier decades. Copper coins are very rare after 402, although minted silver and gold coins from hoards indicate they were still present in the province even if they were not being spent. By 407 there were no new Roman coins going into circulation, and by 430 it is likely that coinage as a medium of exchange had been abandoned. Pottery mass production probably ended a decade or two previously; the rich continued to use metal and glass vessels, while the poor probably adopted leather or wooden ones.
By tradition, the pagan Saxons were invited by Vortigern to assist in fighting the Picts and Irish, though archaeology has suggested some official settlement as landed mercenaries as early as the third century. Germanic migration into Roman Britannia may well have begun much earlier even than that. There is recorded evidence, for example, of Germanic Roman auxiliaries being brought to Britain in the first and second centuries to support the legions. The new arrivals rebelled, plunging the country into a series of wars that eventually led to the Saxon occupation of Lowland Britain by 600. Around this time many Britons fled to Brittany (hence its name). Similar orders were sent out in the 490s but met with no response. A significant date in sub-Roman Britain is the famous Groans of the Britons, an unanswered appeal to Aëtius, leading general of the western Empire, for assistance against Saxon invasion in 446; another is the Battle of Dyrham in 577, after which the significant cities of Bath, Cirencester and Gloucester fell and the Saxons reached the western sea.
Most scholars reject the historicity of the later legends of King Arthur, which seem to be set in this period, but some such as John Morris see it as evidence behind which may lie a plausible grain of truth.
By the time of the Roman occupation, Britain's tin exports to the Mediterranean had been largely eclipsed by the more convenient supply from Iberia. Gold, tin, iron, lead, silver, jet, marble and pearls however were all exploited by the Romans in Britain along with more everyday commodities such as hunting dogs, animal skins, timber, wool and slaves. Foreign investment created a vigorous domestic market, and imports to Roman Britain were often of exotic continental items such as fine pottery such as Samian, olive oil, lavastone querns, fine glassware, wines, garum and fruit.
Mineral extraction sites such as the Dolaucothi gold mine was probably first worked by the Roman army from ca 75 AD, and at some later stage passed to civilian operators. The mine developed as a series of opencast workings, mainly by the use of hydraulic mining methods. They are described by Pliny the Elder in his Naturalis Historia in great detail. Essentially, water supplied by aqueducts was used to prospect for ore veins by stripping away soil to reveal the bedrock. If veins were present, they were attacked using fire-setting and the ore removed for crushing and comminution. The dust was washed in a small stream of water and the heavy gold dust and gold nuggets collected in riffles. The diagram at right shows how Dolaucothi developed from ca 75 AD through to the first century. When opencast work was no longer feasible, tunnels were driven to follow the veins. The evidence form the site shows advanced technology probably under the control of army engineers.
The Wealden ironworking zone, the lead and silver mines of the Mendip Hills and the tin mines of Cornwall seem to have been private enterprises leased from the government for a fee. Although mining had long been practised in Britain (see Grimes Graves), the Romans introduced new technical knowledge and large-scale industrial production to revolutionise the industry. It included hydraulic mining to prospect for ore by removing overburden as well as work alluvial deposits. The water needed for such large-scale operations was supplied by one or more aqueducts, those surviving at Doalucothi being especially impressive. Many prospecting areas were in dangerous, upland country, and, although mineral exploitation was presumably one of the main reasons for the Roman invasion, it had to wait until these areas were subdued.
Although Roman designs were most popular, rural craftsmen still produced items derived from the Iron Age La Tène artistic traditions. Local pottery rarely attained the standards of the Gaulish industries although the Castor ware of the Nene Valley was able to withstand comparison with the imports. Most native pottery was unsophisticated however and intended only for local markets.
By the third century, Britain's economy was diverse and well-established, with commerce extending into the non-Romanised north. The design of Hadrian's Wall especially catered to the need for customs inspections of merchants' goods.
To assist him in legal matters he had an adviser, the legatus iuridicus, and those in Britain appear to have been distinguished lawyers perhaps because of the challenge of incorporating tribes into the imperial system and devising a workable method of taxing them. Financial administration was dealt with by a procurator with junior posts for each tax-raising power. Each legion in Britain had a commander who answered to the governor and in time of war probably directly ruled troublesome districts. Each of these commands carried a tour of duty of two to three years in different provinces. Below these posts was a network of administrative managers covering intelligence gathering, sending reports to Rome, organising military supplies and dealing with prisoners. A staff of seconded soldiers provided clerical services.
Colchester was probably the earliest capital of Roman Britain, but it was soon eclipsed by London with its strong mercantile connections.
Cities and towns which have Roman origins, or were extensively developed by them, include: (with their Latin names in brackets)
The degree to which earlier native beliefs survived is difficult to gauge precisely. Certain northern European ritual traits such as the significance of the number 3, the importance of the head and of water sources such as springs remain in the archaeological record, but the differences in the votive offerings made at Bath before and after the Roman conquest suggest that continuity was only partial. Worship of the Roman Emperor is widely recorded, especially at military sites. The founding of a temple to Claudius at Camulodunum was one of the impositions that led to the revolt of Boudica.
The Church in Britain seems to have developed the customary diocesan system as evidenced from the records of the Council of Arles in Gaul in 314. Represented at the Council were bishops from thirty-five sees from Europe and North Africa, including three bishops from Britain: Eborius of York, Restitutus of London, and Adelphius. Christianity was legalised in the Roman Empire by Constantine I in 313. Theodosius I made Christianity the state religion of the empire in 391, and by the 5th century it was well-established. Saint Alban, the first British Christian martyr, is believed to have died in the early 4th century (although some date him in the middle 3rd century), followed by Saints Aaron and Julius of Isca Augusta. One heresy, Pelagianism, was originated by a British monk teaching in Rome: Pelagius lived c. 354 to c. 420/440.
A letter found on a lead tablet in Bath, datable to c. 363, has been widely publicized as documentary evidence regarding the state of Christianity in Britain during Roman times. According to its first translator, it was written in Wroxeter by a Christian man called Vinisius to warn a Christian women called Nigra of the arrival of Bilonicus, describing him as a canem Arii, an "Arian dog", indicating that the struggle between orthodoxy and heresy was present in Britain as elsewhere in the empire. However, this translation of the letter was apparently based on grave paleographical errors, and the text, in fact, has nothing to do with Christianity.
Britain is also noteworthy as having the largest European region of the former Roman Empire that currently speaks neither (as a majority language):
Significant Germanic migration to Britain seems to have taken place only after the coming of the Romans. The Germanic speakers came originally as Roman auxiliary troops to support the Romans in their conquest of the Celts.
Many British people now have Roman and other Mediterranean ancestry, although in most cases it is mixed in with other ethnicities over the last two millennia. This is not to be confused with more recent admixture (see Italian Britons).