Hadrian's Wall is a former defensive fortification of the Roman province of Britannia, begun in AD 122 in the reign of the Emperor Hadrian. Running from Wallsend on the River Tyne in the east to Bowness-on-Solway in the west of what is now northern England, it was a stone wall (in its final version) with large ditches in front and behind, stretching across the whole width of the island. Soldiers were garrisoned along the line of the wall in large forts, smaller milecastles, and intervening turrets. In addition to the wall's defensive military role, its gates may have been customs posts.
Hadrian's Wall Path generally runs close along the wall. Almost all the standing masonry of the wall was removed in early modern times and used for local roads and farmhouses. None of it stands to its original height, but modern work has exposed much of the footings, and some segments display a few courses of modern masonry reconstruction. Many of the excavated forts on or near the wall are open to the public, and various nearby museums present its history. The largest Roman archaeological feature in Britain, it runs a total of 73 miles (117.5 kilometres). Regarded as a British cultural icon, Hadrian's Wall is one of Britain's major ancient tourist attractions. It was designated a UNESCO World Heritage Site in 1987. The turf-built Antonine Wall of AD 142 in what is now central Scotland, which briefly superseded Hadrian's Wall before being abandoned, was declared a World Heritage Site in 2008.
Hadrian's Wall lies entirely within England and has never formed the Anglo-Scottish border, though it is sometimes loosely or colloquially described as such.
Dimensions
The length of the wall was 80 Roman miles, equivalent to 73 modern miles or 117 kilometres (1 Roman mile is equivalent to 1,620 yards or 1,480 metres). This traversed the entire width of the island, from Bowness-on-Solway in the west to Wallsend on the River Tyne in the east. Not long after construction began, the wall's thickness was reduced from the originally planned 10 feet (3.0 m) to about 8 feet (2.4 m), or even less depending on the terrain. Some sections were originally constructed of turf and timber, eventually replaced by stone years or decades later.
None of the wall stands to its original height. Bede, a monk and historian who died in 735, wrote that the wall stood 12 feet (3.7 metres) high, with evidence suggesting it could have been a few feet higher at its formation. Along the length of the wall there was a watch-tower turret every third of a mile, also providing shelter and living accommodation for Roman troops.
Route
Hadrian's Wall extended west from Segedunum at Wallsend on the River Tyne, via Carlisle and Kirkandrews-on-Eden, to the shore of the Solway Firth, ending a short but unknown distance west of the village of Bowness-on-Solway. The route was slightly north of Stanegate, an important Roman road built several decades earlier to link two forts that guarded important river crossings: Corstopitum (Corbridge) on the River Tyne and Luguvalium (Carlisle) on the River Eden. The modern A69 and B6318 roads follow the course of the wall from Newcastle upon Tyne to Carlisle, then along the northern coast of Cumbria (south shore of the Solway Firth).
Part of the central section of the wall follows natural cliffs on an escarpment of the Whin Sill rock formation.
Although the curtain wall ends near Bowness-on-Solway, this does not mark the end of the line of defensive structures. The system of milecastles and turrets is known to have continued along the Cumbria coast as far as Risehow, south of Maryport. For classification purposes, the milecastles west of Bowness-on-Solway are referred to as Milefortlets.
Purpose
Hadrian's Wall was probably planned before Hadrian's visit to Britain in 122. According to restored sandstone fragments found in Jarrow which date from 118 or 119, it was Hadrian's wish to keep "intact the empire", which had been imposed on him via "divine instruction". On Hadrian's accession to the imperial throne in 117, there was unrest and rebellion in Roman Britain and from the peoples of various conquered lands across the empire, including Egypt, Judea, Libya and Mauretania. These troubles may have influenced his plan to construct the wall, as well as his construction of frontier boundaries now known as limes in other areas of the empire, such as the Limes Germanicus in modern-day Germany.
The novelty of the wall as a departure from traditional Roman military architecture as typified by the Roman limes has been seen as noteworthy and has led to exceptional suggestions of influence by some scholars; for example, David Breeze and B. Dobson suggest "Hadrian may have been influenced by travellers' accounts of the Great Wall of China, built some two hundred years before." This proposal has been challenged by other scholars like Duncan B. Campbell who argues that, though the scale and design of the wall was novel for Roman military construction, "there was a long tradition of wall-building in the ancient (Mediterranean) world upon which he could have drawn for inspiration without the inconvenience of traversing whole continents in search of a prototype."
In recent years, despite the evidence of the wall's over 270-year manned presence, some scholars have disagreed with the established narrative over how much of a threat the inhabitants of northern Britain presented to the Romans, and whether there was any economic advantage in defending and garrisoning a fixed line of defences like the wall, rather than conquering and annexing what has become Northumberland and the Scottish Lowlands and then defending the territory with a looser arrangement of forts. Hadrian and his advisers however produced a solution to their problems that remained relevant for centuries.
The primary purpose of the wall was as a physical barrier to slow the crossing of raiders, people intent on crossing its line for animals, treasure, or slaves, and then returning with their loot. The Latin text Historia Augusta states:
(Hadrianus) murumque per octoginta milia passuum primus duxit, qui barbaros Romanosque divideret.
Translation:
(Hadrian) was the first to build a wall, eighty miles long, to separate the Romans from the barbarians.
The defensive characteristics of the wall support interpretation, including the pits known as cippi frequently found on the berm or flat area in front of the wall. These pits held branches or small tree trunks entangled with sharpened branches. These would make an attack on the wall even more difficult. It might be thought of as the Roman equivalent of barbed wire, a measure to delay an enemy attack and hold the attackers within range of the missiles of the defenders. The curtain wall was not mainly a continuously-embattled defensive line, rather it would deter casual crossing and be an observation point that could alert Romans of an incoming attack and slow down enemy forces so that additional troops could arrive for support.
Besides a defensive structure made to keep people out, the wall also kept people within the Roman province. Movement would be channeled through the gates in the wall, where it could be monitored for information, prevented or permitted as appropriate, and taxed.
The wall would also have had a psychological impact:
For nearly three centuries, until the end of Roman rule in Britain in 410 AD, Hadrian's Wall was the clearest statement of the might, resourcefulness, and determination of an individual emperor and of his empire.
The wall was also a symbolic statement of Rome's imperial power, marking the border between the so called civilized world and the unconquered barbarian wilderness. As British archaeologist Neil Faulkner explains, "the wall, like other great Roman frontier monuments was as much a propaganda statement as a functional facility". There is some evidence that Hadrian's Wall was originally covered in plaster and then whitewashed: its shining surface would have reflected the sunlight and been visible for miles around.
Construction
Hadrian ended his predecessor Trajan's policy of expanding the empire and instead focused on defending the current borders, namely at the time Britain. Like Augustus, Hadrian believed in exploiting natural boundaries such as rivers for the borders of the empire, for example the Euphrates, Rhine and Danube. Britain, however, did not have any natural boundaries that could serve the purpose of dividing the province controlled by the Romans from the Celtic tribes in the north.
With construction starting in 122, the entire length of the wall was built with an alternating series of forts, each housing 600 men, and manned milecastles, operated by "between 12 and 20 men". It took six years to build most of Hadrian's Wall with the work coming from three Roman legions – the Legio II Augusta, Legio VI Victrix, and Legio XX Valeria Victrix, totalling 15,000 soldiers, plus some members of the Roman fleet. The building of the wall was not out of the area of expertise for the soldiers; some would have trained to be surveyors, engineers, masons, and carpenters.
"Broad Wall" and "Narrow Wall"
R. G. Collingwood cites evidence for the existence of a broad section of the wall and conversely a narrow section. He argues that plans changed during construction of the wall, and its overall width was reduced. Broad sections of the wall are around nine and a half feet (2.9 metres) wide with the narrow sections two feet (61 centimetres) thinner, around seven and a half feet (2.3 metres) wide. Some of the narrow sections were found to be built upon broad foundations, which had presumably been built before the plans changed.
Based on this evidence, Collingwood concludes that the wall was originally to be built between present-day Newcastle at its eastern end and Bowness-on-Solway at its western end, with a uniform width of 10 Roman feet, all in stone. On completion, only three-fifths of the wall was built from stone; the remaining western section was a turf wall, later rebuilt in stone. Plans possibly changed due to a lack of resources. In an effort to preserve resources further, the eastern half's width was therefore reduced from the original ten Roman feet to eight, with the remaining stones from the eastern half used for around 5 miles (8.0 kilometres) of the turf wall in the west. This reduction from the original ten Roman feet to eight created the so-called "Narrow Wall".
Vallum
Just south of the wall there is a deep, ditch-like construction with two parallel mounds running north and south of it, known as the Vallum. The Vallum and the wall run more or less in parallel for almost the entire length of the wall, except between the forts of Newcastle and Wallsend at the east end, where the Vallum may have been considered superfluous as a barrier on account of the close proximity of the River Tyne. The twin track of the wall and Vallum led many 19th-century thinkers to note and ponder their relation to one another.
Some evidence appears to show that the route of the wall was shifted to avoid the Vallum, possibly pointing to the Vallum being an older construction. R. G. Collingwood therefore asserted in 1930 that the Vallum was built before the wall in its final form. Collingwood also questioned whether the Vallum was an original border built before the wall. Based on this, the wall could be viewed as a replacement border built to strengthen the Romans' definition of their territory.
In 1936, further research suggested that the Vallum could not have been built before the wall because the Vallum avoided one of the wall's milecastles. This new discovery was continually supported by more evidence, strengthening the idea that there was a simultaneous construction of the Vallum and the wall.
Other evidence still pointed in other, slightly different directions. Evidence shows that the Vallum preceded sections of the Narrow Wall specifically; to account for this discrepancy, Couse suggests that either construction of the Vallum began with the Broad Wall, or it began when the Narrow Wall succeeded the Broad Wall but proceeded more quickly than that of the Narrow Wall.
Turf wall
From Milecastle 49 to the western terminus at Bowness-on-Solway, the wall was originally constructed from turf, possibly due to the absence of limestone. Subsequently, the turf wall was demolished and replaced with a stone wall. This took place in two phases; the first (from the River Irthing to a point west of Milecastle 54) during the reign of Hadrian, and the second following the reoccupation of Hadrian's Wall after the abandonment of the Antonine Wall (though it has also been suggested that this second phase took place during the reign of Septimius Severus). The line of the stone wall follows the line of the turf wall, apart from the stretch between Milecastle 49 and Milecastle 51, where the line of the stone wall is slightly further to the north.
In the stretch around Milecastle 50TW, it was built on a flat base with three to four courses of turf blocks. A basal layer of cobbles was used westwards from Milecastle 72 (at Burgh-by-Sands) and possibly at Milecastle 53. Where the underlying ground was boggy, wooden piles were used.
At its base, the turf wall was 6 metres (20 feet) wide, built in courses of turf blocks measuring 46 cm (18 inches) long by 30 cm (12 inches) deep by 15 cm (6 inches) high, to a height around 3.66 metres (12.0 feet). The north face is thought to have had a slope of 75%, whereas the south face is thought to have started vertical above the foundation, quickly becoming much shallower.