Belsar’s Hill is an oval shaped fort that, before modern drainage, was located on an island of firm ground amongst the inaccessible Fens. The earthwork may have been built during the Iron Age to serve as a border fortress. Alternatively the facility could have been constructed by the Normans in 1071 as a temporary base from which to suppress the rebellion of Hereward the Wake.



Belsar's Hill is an oval shaped fortification enclosing around 6 acres and located on what was once an island of firm ground on the edge of the Fens which before modern drainage was a vast area of waterlogged terrain, thick shrubs and numerous rivers. The defences consisted of a single 12 metre wide ditch, which was probably seasonally flooded, and a substantial rampart. The original entrance to the site was on west side adjacent to the track that runs through the site. The date of this road is uncertain but is probably nineteenth century in origin when the Aldreth Causeway was redirected over the site of Belsar's Fort. Previously this historic causeway had skirted around the earthworks connecting the Isle of Ely with Cambridge.


Little is known about the history of Belsar's Hill. Some have mooted it was originally an Iron Age univallate hillfort. It certainly resembles other fortifications known to have been built at this time such as Arbury Camp or Wandlebury. If so the fort was located on the borderland between the Iceni and Catuvellauni tribes and may have marked the extremities of their territory.


An alternative narrative suggests Belsar's Hill is a post-Conquest structure either wholly built by the Normans or adapted by them as a temporary base. Certainly a large Norman army was in the vicinity in 1071 following the rebellion of Hereward the Wake. He had mobilised the region due to the imposition of a Norman Abbot at Peterborough which had resulted in many of the native English landowners being dispossessed in favour of Norman immigrants. Hereward was supported by King Sweyn of Denmark and this represented a significant threat to the Norman regime prompting William I to personally lead a large army to suppress the revolt. Hereward retreated to the Isle of Ely which was protected by the surrounding fenland and which frustrated the use of cavalry, the Norman's primary (and normally decisive) weapon. To access the island, the Normans built a mile-long causeway extending from Belsar's Hill but it sank under the weight of the armoured Norman troops as they advanced. Eventually the Normans were able to bribe a local monk to show them a safe route through the Fens onto the island. Ely was stormed and the rebellion defeated although the fate of Hereward is uncertain.


The full history of Belsar's Fort will remain a mystery until archaeological evidence produces a definitive find. Observations of the site suggest the Iron Age origin a may be correct - as evidenced by the original entrance in the north-east and north sides - but which was later adapted by the Normans to place the entrances along the Aldreth Road. However, to date this is just speculation and nothing has been found that assists in dating the structure to any specific period.




Douglas, D.C and Greeaway, G.W (ed) (1981). English Historical Documents Vol 2 (1042-1189). Routledge, London.

Historic England (2016). Belsar's Hill Ringwork List entry Number: 1010368. Historic England, London.

Huscroft, R (2009). The Norman Conquest: A New Introduction. Pearson Education Limited, Harlow.

Ordnance Survey, Historic England and RCAHMW (2016). Ancient Britain. 1:625,000 Scale. Ordnance Survey, Southampton.

Phillips, P (1948). Cambridgeshire and the Isle of Ely Vol. 2. VCH.

Renn, D.F (1973). Norman Castles of Britain. John Baker, London.

Taylor, A (1986). Castles of Cambridgeshire. Cambridge.



What's There?

Belsar's Hill Fort is an oval shaped earthwork of unknown origin. The ditch survives to a depth of around 1 metre and the rampart up to a height of around 2 metres - both significantly reduced from their heyday but still impressive. The road that runs through the site is a public right of way although the fort ramparts and ditches are on private land.

Belsar's Hill. The fort consisted of a single ditch and rampart but these defences would have been greatly enhanced by the surrounding fenland which was waterlogged terrain making access difficult. The name of the site suggests a Norman origin - the earliest written record lists it as Bellassise which derives from Old French meaning 'beautiful seat'.

Norman Assault on the Isle of Ely. Prior to modern drainage the Fens were a large area of waterlogged and inaccessible terrain. When the Normans sought to dislodge Hereward the Wake from his base on the Isle of Ely in 1071, they first attempted to build a mile long causeway from Belsar's Hill. This sunk under the weight of the troops and eventually they had to bribe a monk to show them an existing route through the marsh.

Aldreth Causeway. As Cambridge grew in importance a causeway emerged connecting it with the Isle of Ely. This originally skirted around Belsar's Hill but the road was re-routed in the nineteenth century to run through the centre of the fort. The route remains a public right of way today and accordingly offers access to the fort.

Getting There

Belsar's Hill is found off Iram Drive which is accessed from Priest's Lane to the east of Willingham. The site is not sign-posted but an information board adjacent to the road marks the site. Parking for a small number of cars is possible in the immediate vicinity.

Belsar's Hill Fort

CB24 5HZ

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