The village of Earith stands on the edge of the Cambridgeshire fens (low-lying wetlands subject to seasonal flooding) on the River Ouse. Just to the east of the village, the river split into two branches, one flowing north and one flowing east. The road between Huntingdon and Ely crossed the north branch of the river, giving Earith the name Gateway to the Isle of Ely. Just to the north of the place where the river splits there lies a Civil War fort known as Earith Bulwark.
In the 1630s a Dutch hydraulic engineer named Cornelius Vermuyden was employed by the Earl of Bedford to drain the fenland. He made a cut leading from the River Ouse at Earith to the sea at King's Lynn, taking excess water from the river north-east to Denver across the fens.
This new channel, called the Forty Foot Drain or the Bedford River, helped to drain the fens by removing some of the water from the River Ouse, that winds its way through the wetlands, and taking it directly to the estuary. The Forty Foot Drain was completed in 1637 and it was partly successful in draining the fens, although flooding in the winter was still common.
At the outbreak of the English Civil Wars'in 1642 all of the south-east of England, including London, sided with parliament. Many people living in the fens bore a particular hatred for the Royalists because of the king's drainage projects, which had damaged their livelihoods.
The Royalist territory included the northern counties, extending as far south as Lincolnshire. For the first few years of the Civil War there was the constant threat of an advance on East Anglia and Cambridge from the north, which would bring the Royalists dangerously close to London. The Eastern Association, a combined force of Parliamentarian militias from the eastern counties, in which Oliver Cromwell served, was responsible for defending the frontier.
It is difficult to establish historical facts about the fort at Earith, because there is no direct reference to it in the records of the time, but it seems likely that construction of the fort began in early 1643 when the Eastern Association was on the defensive.
In April 1643, the Royalists occupied Peterborough and in response Cromwell ordered the fortification of a number of crossing points of the River Ouse to form a barrier to stop the enemy advance. The Earith Bulwark was probably constructed as part of this scheme to protect the bridge where the Ely road crosses the river.
Although the fighting moved away to the north after a few weeks, a pro-Royalist uprising in Ely later in the year demonstrated the need for a continued Parliamentarian military presence. The fort at Earith remained important, guarding the Gateway to the Isle of Ely.
A member of the Eastern Association suggested that if the Isle of Ely was lost to the Royalists it would become "a stronghold like Dunkirk to plunder all our Countys", a reference to the French privateers that operated very successfully out of Dunkirk to plunder shipping in the English Channel.
The Earith Bulwark consists of a square earthwork fort with bastions'at the corners. There is a ditch'at the foot of the rampart and a covered way. A hornwork'extends north-west, but it is only formed by the covered way, there is no rampart.
Beyond the covered way there is a second ditch. There are no demi-lunes'but the covered way does widen out in front of the curtains, forming a salient. Given the wet nature of the land at the time, it is likely that the ditches were flooded, or at least soft underfoot. Archeological surveys suggest that a second hornwork, of which little remains, may have extended southwards towards the road.
The fort is unmistakably Dutch in its character and design, especially the earthwork construction and the use of a second ditch beyond the covered way. It is similar in size to contemporary forts in the Netherlands, such as Fort Nassau at Retranchement.
During the Eighty Years War'in the Netherlands, fieldworks of this size and form, called sconces, were commonly constructed to protect key locations. Both the Parliamentarian and the Royalist armies had men in their ranks who had served in the Netherlands, who would have been familiar with modern fortifications.
It is possible that the design of the Earith Bulwark was carried out by a Parliamentarian officer who had served in the Netherlands, but the work shows a degree of professionalism that suggests it was made by someone who had experience of military engineering.
We can speculate that one of the known engineers serving with the Parliamentarian forces (such as the Dutchman Cornelius van den Boom) was responsible for the design of the fort, but in reality it is impossible to know the authorship of the work without documentary evidence.
After the Civil Wars the drainage schemes were re-implemented with the digging of a new cut, called the New Bedford River, starting from the north branch of the River Ouse and running parallel with the Forty Foot Drain, now known as the Old Bedford River.
With the completion of this new channel in 1652, the fort lay on the strip of land between the two Bedford Rivers, which was designed to flood in the winter. Interestingly, during the Second World War a machine gun turret was built on the south bastion, showing that the location was still considered strategically important 300 years after the Civil War.
The frequent flooding of the site over the last 350 years has taken its toll on the Earith Bulwark, but nevertheless the earthworks, although decayed have survived, preserving the form of the fort to this day.
The fort's design can be appreciated easily from the remains, although in places the outer edge of the covered way and second ditch have almost disappeared. It is crossed by two lines of trees, but these detract little from its appearance.
The Earith Bulwark is in a field next to the A1123 road, between the Old Bedford River and the New Bedford River on the eastern edge of Earith village. A public bridleway leads across the site, which is marked on the Ordinance Survey map (grid reference TL3975) but can be difficult to find on the ground. The entrance to the bridleway is the old rusty gate on the right as you walk up the right hand bank of the Old Bedford River.
The best way to see the Earith Buwlark is from above. The aerial view of the Earith Bulwark below was taken by Steve Wilson from a microlight (Photograph property of Steve Wilson. All rights reserved):