27. Were turf walls common in the Roman empire?

Turf walls (and other forms of earthen ramparts) were often used for fortifications in the 1st century AD, particularly in Britain. They were employed for both auxiliary forts and legionary fortresses, and were standard for temporary camps used when on the march or on campaign. Vegetius describes how they were constructed. They were not commonly used for frontiers, however, Hadrian’s Wall being the first and the Antonine Wall the second, so far as we know.

Further reading: Milner 1995

26. Does any of the Hadrian’s Wall Turf Wall survive?

For most of its length, the Turf Wall was levelled and the replacement narrow gauge stone curtain wall built directly on top of it, retaining the same ditch. However, between Milecastles 49 and 51 the new Stone Wall was built further north, and that means that the Turf Wall and its ditch survive as earthworks here, immediately north of the Vallum. This section was first excavated in 1895 and periodically re-examined.

There is one additional area where the Stone Wall deviates from the course of the Turf Wall and that is where Turret 54A collapsed into the Turf Wall ditch and its replacement was built just behind it; here the stone curtain wall was realigned to join the newer turret.

Further reading: Breeze 2006; Symonds and Mason 2009

25. Why was the Turf Wall built?

Some scholars have suggested that the reason for the use of a turf rampart may have been the difficulty in obtaining good building stone on the western side of the country or even the difficulty in obtaining limestone to make lime for mortar. Nevertheless, the stone curtain wall was later extended all the way to Bowness, using St Bees sandstone, probably after the final abandonment of the Antonine Wall in the mid-AD 160s, so perhaps the problem was that these materials could not be obtained and assembled quickly enough to complete the project in good time. The Emperor Hadrian himself commented to troops in North Africa that it normally took longer to construct a stone wall than an equivalent turf rampart.

Further reading: Breeze and Dobson 2000

24. What is the Turf Wall?

The original scheme for Hadrian’s Wall consisted of a stone curtain wall between Newcastle and the river Irthing (Wall Miles 4 to 48) and then a turf rampart from the Irthing to Bowness (49 to 79). The rampart was built on a base about 6m (20 Roman feet) wide with no foundation trench, in some places just laid turves, in others cobbles were used, but it seems to have depended what materials were available. The rear face sloped at an angle of about 67° and the front was vertical near the base and then probably sloped above.

The Turf Wall was equipped with turf and timber milecastles but stone turrets. These turrets, built free-standing and with the turf rampart then butted against them, were retained when the stone curtain wall was built (suggesting the walkway, if there was one, stayed at the same height). The ditch that was dug for the Turf Wall was retained for the Stone Wall, although the berm increased in width from around 1.9–2.4m (6–8 Roman feet) to 6m (20 Roman feet).

It is assumed there was some sort of wooden superstructure, such as a walkway and parapet, but almost no evidence has survived to support this. The one clue that there might have been a walkway comes from the fact that when the Turf Wall was replaced by a stone curtain, that stone wall was set back slightly from the front of the turrets. Some scholars have suggested this shows it was lined up with existing doorways on the turrets giving access to a walkway.

Further reading: Breeze and Dobson 2000; Symonds and Mason 2009

23. Was Hadrian’s Wall always the most northerly frontier of Roman Britain?

No. Soon after Hadrian died in AD 138 and he was succeeded by his adoptive son, Antoninus Pius, work began on a new mural barrier across the Forth–Clyde isthmus. This time, like the Turf Wall, it was an earthen rampart on a stone base, but it was also much shorter, with fewer and smaller forts, and would have required fewer men to garrison it. However, it was abandoned within 25 years of its construction and Hadrian’s Wall was recommissioned as the most northerly frontier in the Roman Empire.

Further reading: Breeze and Dobson 2000

22. Was Hadrian’s Wall the first frontier in Britain?

Various lines have been claimed as early ‘frontiers’ for Roman Britain, starting with the Severn–Trent (or Fosse Way) line, the Gask Ridge in Scotland, and the Stanegate in Northumberland and Cumbria, but Hadrian’s Wall is undoubtedly the first mural barrier and, as such, an indisputable frontier. Most of the other claimants can be dismissed as fortified roads by the sceptical.

Further reading: Breeze and Dobson 2000

21. Did Hadrian’s Wall change after it was built?

Just as it changed whilst being built, so it changed afterwards. The Romans began to replace the Turf Wall with a stone curtain between the Irthing and Milecastle 54 before the Wall was abandoned in favour of the Antonine Wall, only to resume that process when they subsequently returned to it. That very abandonment and reoccupation led to changes too. Turrets were abandoned and some even demolished, a fort added at Newcastle, and the bridges at Willowford and Chesters (and perhaps Carlisle too) were rebuilt on a grander scale, probably during the latter part of the 2nd century AD (although not necessarily all at the same time).

There was also substantial rebuilding of the curtain wall under Septimius Severus, making up for the deficiencies of the earlier structure and the ravages of time.

Further reading: Breeze and Dobson 2000