Shropshire History


Wat’s and Offa’s Dykes


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Wat’s Dyke




King Aethelbald of Mercia expanded his control over most of southern England during his reign but, in 740, there was a revolt by the Saxons in Wessex. In 743 he was at war with the Welsh on his borders so, to guard his rear while he dealt with the southern enemies, he constructed a linear earthwork that became known as Wat’s Dyke.  This stretched intermittently for 37 miles from the River Morda at Maesbrook to Basingwerk on the Dee Estuary at Holywell. It consists of a bank with a ditch on its west side, presenting a barrier to the west. It thus predates Offa's Dyke, to which it runs parallel for part of its length. The Dyke is now a Scheduled Monument.






Maesbrook (SJ301219) - Redwith (SJ30432453)

The dyke is supposed to start at the River Morda but there is no obvious trace.  Presumably it has been ploughed out but a possible start is at a bend in the river at Maesbrook. Aerial photography has revealed crop marks of a 1,200 yds section of the dyke between SJ303233 and SJ304244. A modern hedgerow follows the line of the dyke for part of the way and it is probable that remains of the original bank survive beneath the hedgerow.


Redwith (SJ30432453) – Oswestry (SJ293297)

Crop marks indicate that it meets and follows the line of the Montgomery Canal here to Croft’s Mill Bridge. From here to Oswestry it possibly follows the line of minor roads and footpaths north-west from SJ304249. In Oswestry, traces of the dyke have been found at the southern edge of the former railway marshalling yard.

Oswestry (SJ293297) – Pentre-clawdd (

The route heads north through Oswestry to Old Oswestry hillfort, where a short section is visible south of the fort at SJ293307. Two sections of the dyke (measuring 328 yds and 185 yds) are visible as a single bank north of the fort between SJ29723173 - SJ29923238. 


Pentre-Wern (SJ300326) – Gobowen (SJ302333)

A section is visible for 142 yds to the south side of the embankment of the B5069 to Pentre Dafydd (SJ301329). It survives as a 2ft high bank with traces of a ditch to the west. The remains are about 75ft wide in this section. At either end the remains are truncated by the construction of both the A5 and the B5069. At SJ301330 there is a V-shaped ditch, 26ft wide by 12ft deep, with a 1ft high rampart to the east. The latter consists of a clay bank topped by a massive dump of stone, with no berm between rampart and ditch. At SJ30203321 there is a V-shaped ditch, 26ft wide and 9ft deep with an ankle-breaker slot in the base.  There is an earth and stone bank on the eastern side, 16ft in width and 2ft in height. No timber was used in its construction, although evidence for a marker bank and a well-laid cobbled foundation show that it was carefully planned. At a point 328 yds south-west of Gobowen Station (SJ302333), a section runs for 153 yds as a 2ft high earthwork bank. There are slight traces of a 13ft wide ditch on the western side of the bank.


Gobowen (SJ302333) – Rhewl (SJ304344)

The dyke passes to the east of Bryn-y-Castell (SJ30393404) and a 72ft long section is visible as a broad, flat depression, about 22ft wide, to the north east of the castle mound. The western side of the ditch is discernible as a scarp, which has cut into the natural slope. The infilled part of the ditch here is thought to be as much as 13ft deep but there are no visible indications of an adjacent bank. At SJ30473436 there is a 459 yds section, situated 206 yds west of the junction of Preeshenlle Lane and St Martin's Road.


Rhewl (SJ304344) – Preeshenlle Bridge (SJ308359)

The route here is overlain by a minor road and passed Henlle Hall to Preeshenlle Bridge. At SJ306353 there is a 120 yds section running beside the road. It is a 6ft high bank, 50ft wide at the base, with a ditch on the western side, 20ft wide and 2ft deep. At the north end the remains have been truncated by levelling the garden at The Lodge and at the south end the remains have been obscured by the buildings for Preeshenlle Farm. The remains are clearly visible from the public highway. At SJ30793562 there is a 535 yds section heading north and visible either side of the bridge over the Shropshire Union Canal. It has an 8ft high bank with a ditch to the west. This section terminates at a farm track and brook 142 yds south of Esgob Mill.

Preenshenlle Bridge (SJ308359) – Glynmorlas (SJ313377)

From SJ310361 to SJ310368 the dyke can clearly be followed through woodland to near Fach. Further north it is not so clear but it presumably follows the north-west facing slope to join the Welsh border at Glynmorlas.



Offa’s Dyke




King Offa of Mercia ruled from 747-796 and constantly had problems with warring Welsh tribes in the Marches. In 779, he drove the Welsh King of Powys from Shrewsbury and secured his conquests by building a defensive earthwork that became known as Offa's Dyke. The 10th Century writer Asser said "there was in Mercia in fairly recent time a certain vigorous king called Offa, who terrified all the neighbouring kings and provinces around him and who had a great dyke built between Wales and Mercia from sea to sea". It was constructed from the mouth of the River Dee in the north to that of the River Wye in the south and followed an agreement with the Celts whereby they took back Oswestry.


In all, the earthwork (the longest in Britain) runs for 82 miles of the total distance of 149 miles between Prestatyn in the north to Sedbury in the south, the intervening gaps being filled by natural features such as slopes and rivers. It consists of an earth bank, which in places still stands to a height of 12ft, fronted by a deep ditch with a total width of up to 65ft. Excavation has confirmed that a wooden breastwork ran along the top of the bank and in places this was later rebuilt in stone. The west side of the bank was also revetted with turf to create a near vertical face. Possibly some sort of palisade or wall also existed. It is thought that towers may have been erected at intervals, though none has yet been found. In places it runs absolutely straight for miles and shows the technical skills of its engineers. The earthwork was dug with the displaced soil piled into a bank on the Mercian (eastern) side. Where the earthwork encounters hills, it passes to the west of them, constantly providing an open view from Mercia into Wales. The dyke may have been constructed as a defensive earthwork, as well as a political statement of power and intent.




The work required thousands of men to complete and each section seems to have been built by people from the local district. The fact that this mammoth undertaking was achieved illustrates the cohesion of the kingdom at this time. The dyke was never garrisoned but would have been manned by relatively small local forces. Offa died in 796 in a battle against the Welsh, as he was trying to establish a final link in the Dyke to the Irish Sea in the north. The Dyke is now a Scheduled Monument.


There is an Offa’s Dyke Association and an Offa’s Dyke Centre at Knighton. For those interested in seeing it at close quarters, there are Walking Trails.