Offa’s Dyke: Facts and Information

Here are some interesting facts about Offa’s Dyke.

  • Offa’s Dyke is a large earthwork, which roughly follows the border between England and Wales. In the 8th century, it marked the border between the Anglo-Saxon kingdom of Mercia in England and the Welsh kingdom of Powys.
  • England at that time was divided into several independent kingdoms. Mercia was the largest and the most powerful and stretched from the River Humber to the English Channel.

  • The dyke stretches for 240 km from Prestatyn in North Wales to the River Severn estuary. It is almost 20 metres wide in places, and up to 3.5 metres deep.
  • Most historians believe the dyke was built by Offa, the Anglo-Saxon King of Mercia, from 757 to 796, but in 2014 evidence was unearthed to suggest that it might have been a project undertaken during the reigns of several Mercian rulers.
  • It was a considerable achievement back then to recruit enough men for such a large building project. Offa may have required people living in certain areas to take responsibility for building different sections of the dyke.
  • Offa’s Dyke is one of the most impressive early construction efforts by inhabitants of Britain. It may have been built for defensive reasons, or simply as a visible dividing line between the two kingdoms.
  • The Offa’s Dyke long-distance path was opened in 1971. It crosses the border between England and Wales 20 times and passes through 8 different counties.
  • It takes the average walker about 12 days to walk the length of the path from one marker to the other. Horse riders and cyclists are allowed on about a third of the path.
  • The Offa’s Dyke Path is flat in places, and it is known for the large number of stiles along its route. The highest point on the path is 700 metres at Hatterall Ridge.
  • In 2012, the historian Michael Wood ran the entire length of Offa’s Dyke in just over 2 days and 16 hours. He raised several thousand pounds for charity.
  • More than 3000 people complete the 177 mile Offa’s Dyke Path every year. The record finish time is 52 hours and 26 minutes.
  • The first written record of Offa’s Dyke appears in a 9th century biography of King Alfred by Asser.
  • The dyke is in danger of being destroyed in some places due to natural erosion, damage caused by walkers, agriculture and the activity of rabbits and other animals. It is hard to maintain the dyke because much of it is located on private land.
  • There are many very old oak, sycamore and yew trees growing alongside Offa’s Dyke, including a well-known great oak near Chirk, Wrexham, called the Oak at the Gate of the Dead. It has this name because the tree grows close to the site of the Battle of Crogen, fought between the armies of Henry II and an alliance of Welsh rulers led by Owain Gwynedd in 1165.
  • Archaeologists still don’t know if Offa’s Dyke was built in one go, or whether it was constructed by linking up several pre-existing boundary earthworks and barriers.
  • Some parts of Offa’s Dyke would have incorporated wooden ramparts and it is speculated that there would have been thorny bushes growing in the ditch below.
  • Some historians have suggested that towers might have been placed at intervals along the dyke, but no evidence for such structures has yet been discovered.
  • In the fourth season of The Last Kingdom TV series (based on Bernard Cornwell’s books), one of the characters, Hywell Dda, refers to Offa’s Dyke.
  • In 2021 Rob McBridge completed his tree survey of the Offa’s Dyke Path, cataloging hundreds of trees for the Woodland Trust. One of the yew trees he discovered in Discoed churchyard is estimated to be more than 2500 years old.

What next? Discover more Anglo-Saxon facts by visiting our Anglo-Saxon resources page.

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