The Roman conquest of Anglesey refers to two separate invasions of Anglesey in North West Wales that occurred during the early decades of the Roman conquest of Britain in the 1st century CE. The first invasion of North Wales began after the Romans had subjugated much of southern Britain. It was led by the Provincial governor of Britannia, Suetonius Paulinus, who led a successful assault on the island in 60–61 CE, but had to withdraw because of the Boudican revolt. In 77 CE, Gnaeus Julius Agricola's thorough subjugation of the island left it under Roman rule until the end of Roman rule in Britain in the early 5th century CE. Anglesey was invaded as it was an important centre for the Celtic Druids and their religious practices which made it a place of resistance to Roman rule.
No surviving Roman sources mention Anglesey, which was recorded in Latin as Mona (and is still known as Môn in modern Welsh), after its conquest. Archaeologists have located a fort dated shortly after the first conquest near Cemlyn Bay; a trading settlement on the shore of the Menai Strait; and a village of huts huddled together on a hill for defence. In the last decades of Roman rule in Britain several military forts were built on the northern and western coasts to defend the island against Irish sea raiders. However, despite more than three centuries of Roman rule, archaeologists have found no evidence of major civic centres or villas on the island, indicating that Romano-British culture lacked the influence it had in other parts of the Roman province of Britannia.
The only Roman source for the island's two invasions is the Roman historian Tacitus. His last work The Annals, written as a history of the Roman Empire from Tiberius until Nero, mentions the first invasion by Suetonius Paulinus. The second invasion is detailed in Tacitus's work The Life of Gnaeus Julius Agricola, which was written to record and extol the life and accomplishments of his father-in-law. Tacitus may have used first-hand accounts from Agricola, who had been present with the Roman forces on both occasions.
First invasion (60 CE) The first invasion of Anglesey took place in 60 or 61 CE following Suetonius Paulinus' success in other parts of the province, subjugating British tribes and establishing Roman forts. Tacitus writes: "Britain was in the hands of Suetonius Paulinus, who in military knowledge and in popular favour, which allows no one to be without a rival, vied with Corbulo, and aspired to equal the glory of the recovery of Armenia by the subjugation of Rome's enemies. He therefore prepared to attack the island of Mona which had a powerful population and was a refuge for fugitives." Tacitus, who later married the daughter of Suetonius Paulinus's young aide-de-camp, Gnaeus Julius Agricola, may have heard first-hand accounts of the campaign and even of Suetonius's personal comments.
The decision to invade may also have been motivated by information about copper mines on Anglesey.
Approaching the Menai Strait
Tacitus says: "[Suetonius Paulinus] built flat-bottomed vessels to cope with the shallows, and uncertain depths of the sea. Thus the infantry crossed, while the cavalry followed by fording, or, where the water was deep, swam by the side of their horses."
He does not state where these boats were built, perhaps Deva Victrix (Chester), where a few pre-Flavian coins may indicate an early base whose role would have been tied to the movement of troops by sea along the coasts of north Wales.
Marshy ground to the west of Chester made it a poor base for overland penetration of North Wales, and Suetonius' march to the Menai Strait may have used the oldest known crossing of the River Dee, some 13 km south of Chester at Holt. An army moving on foot along the north coast of Wales would have first seen Anglesey from the mouth of the Sychnant Pass near Abergwyngregyn, where the three land routes converge.
Crossing the Menai Strait The Roman forces then had to cross the Menai Strait, a narrow strip of water some 8km long that separates the island of Anglesey from the rest of the Welsh mainland. The sea crossing would be short and relatively easy at slack water, but at full strength the tidal currents can be up to 7.5 knots with much turbulence in the narrower and rockier sections. Local knowledge, at least a long enough period of observation to predict the tidal currents with reasonable accuracy, would be required to plan safe transit. (The later invasion under Agricola took the natives by surprise because they had expected to see a fleet in plenty of time to gather for their defence of the island.)
The locations of the Menai crossings are not known and modern suggestions are purely speculative. William Manning suggested that a possible site is at the north-eastern end of the Strait, near the present city of Bangor, easily accessible from the Sychnant Pass, where travellers on the mediaeval ferry set out across the Lavan Sands to cross the Strait. The Lavan Sands at low tide would be an appropriate place to ground and load flat-bottomed boats, and to assemble cavalry ready to swim. The path across the sand flats is some 4.5 km, but the sea crossing would be only some 240 metres at the lowest state of the tide. If Suetonius had established a camp a little further west, across the River Ogwen on the present site of Penrhyn Castle, Bangor Flats would have offered access to a similar 240-metre crossing, reached by only some 1.5 km on tidal sand flats. The attackers would need to time their movement across the tidal flats with care, to avoid being caught by the incoming tide before the boats were loaded and the swimming units in position. Both of these locations would require the Roman troops landing on Anglesey to fight up slopes that rise steeply almost from the water's edge, except near Gallows Point where a small peninsula and a stony beach offer some hectares of fairly flat space by the waterside.
The parish of Llanidan is on Anglesey, towards the southwestern end of the Menai Strait. The Llanidan locations require a longer sea crossing (a minimum of some 350 metres between sandbanks at low tide, some 850 metres at high tide),Admiralty Chart BA1464 Menai Straits - SW entrance and offer less violent currents, less turbulence, and gentler slopes up from the sea shore. There are no large sand flats on the mainland side, but there are areas of gentle terrain where troops could have been assembled. A land force moving from the north coast of Wales to cross to Llanidan would have to cross an area of high ground, or move through a glacially-deepened valley between steep slopes that offer possible ambush positions.
Henry Rowlands in the 1700s identified a ford at Porthamel in Llanidan parish, across the Menai Strait from the present site of Felinheli, where he suggested that the Roman cavalry had swum across and the human sacrifice had happened. "As for the place of their landing, and of their routing this religious army, we have no exact account of it. But there are probable grounds to conclude that it was near Porthamel betwixt a place called Pwll y fuwch and Llanidan. For Tacitus says that the horse vado secuti — swam it at the ford : And that ford or shallow is just under Llanidan. And it seems their foot landed in their flat-bottomed vessels near the said Pwll y fuwch; where there is a place called Pant yr yscraphie to this day; the Romans calling such boats Scapha, and we from them Yscraphie, with an addition of one letter, as is usual in these changes. And indeed the mount or Tumulus in one of the fields adjoining, about three bows shot from the sea, seems to be the place of that great sacrifice : whence the Druids took up firebrands in their hands, brandishing them like furies about the army ; and where the Romans involved the taken and slain Britons in the devouring flames of their own sacrifice."
Still within Llanidan parish, further southwest along the Menai Strait, local field names "Maes Hir Gad" (Area of long battle) and "Cae Oer Waedd" (Field of cold or bitter lamentation) were recorded in 1867, with the suggestion that these may indicate the site of a Roman attack.
Opposition The landing was opposed by a mass of warriors, Druids, and women. Tacitus describes the scene: "On the shore stood the opposing army with its dense array of armed warriors, while between the ranks dashed women, in black attire like the Furies, with hair dishevelled, waving brands. All around, the Druids, lifting up their hands to heaven, and pouring forth dreadful imprecations, scared our soldiers by the unfamiliar sight, so that, as if their limbs were paralysed, they stood motionless, and exposed to wounds." Roman soldiers are not often described as scared to paralysis and their reception must have been an extraordinary experience even for professional soldiers.
However, the Romans rallied, and won a brutal victory over people who they regarded as savages. Tacitus reports: "Then urged by their general's appeals and mutual encouragements not to quail before a troop of frenzied women, they bore the standards onwards, smote down all resistance, and wrapped the foe in the flames of his own brands."
Garrison, destruction of sacred groves Tacitus suggests that the Romans then had time to make their occupation of the island effective. "A force was next set over the conquered, and their groves, devoted to inhuman superstitions, were destroyed. They deemed it indeed a duty to cover their altars with the blood of captives and to consult their deities through human entrails." The Iron Age settlement between Bryn Celli Ddu (Black Grove Hill) and Llanddaniel Fab, on a landscape of more ancient Neolithic and Bronze Age tombs, may have been a centre of Druidic practice and a target of Suetonius's invasion.Woods, Mike (2026). The Dark Side of the Tomb: a landscape study utilizing archaeological excavation, multi-modal geophysical survey and imaging techniques of the Neolithic and Early Bronze Age monuments on the Isle of Anglesey, North Wales. Manchester Metropolitan University. Thesis. https://doi.org/10.83056/mmu.32483082.v1 p.291 accessed 19 September 2026
Romans abandon the island The Roman army shortly received serious news from southern Britain. Tacitus writes: "Suetonius while thus occupied received tidings of the sudden revolt of the province..." "Suetonius, however, with wonderful resolution, marched amidst a hostile population to Londinium..."
The Roman troops left Anglesey, which remained free from Roman rule for sixteen years until the second invasion under Agricola.
Between Roman attacks After the Boudican revolt, the conquest of Wales was put on hold. Between Suetonius and Agricola, the province of Britannia had five British governors but none undertook any further military campaigns in the regions known as Cambria. In general the Romans, affected by social and military conflicts throughout the Empire, unrest in the legions garrisoned in Britain, and the aftermath of Boudica's rebellion, did not try to take more territory in this phase. Only after Vespasian became emperor in 69 CE was the conquest of Wales resumed, as Tacitus records in his book The Life of Gnaeus Julius Agricola. Agricola's predecessor Julius Frontinus arrived in 74 CE to resume the conquest of Wales. Tacitus only gives one line about Frontinus, claiming he subdued the powerful Silures tribe in South Wales. He continues: "Such was the state of Britain, and such were the vicissitudes of the war, which Agricola found on his crossing over about midsummer. Our soldiers made it a pretext for carelessness, as if all fighting was over, and the enemy were biding their time."
Second invasion (77 CE)