|Region||East of England and East Midlands|
|Counties||Lincolnshire, Cambridgeshire, Norfolk; parts of Suffolk and Huntingdonshire|
|• Total||1,500 sq mi (3,900 km2)|
|Time zone||UTC±0 (Greenwich Mean Time)|
|• Summer (DST)||UTC+1 (British Summer Time)|
The Fens, also known as the Fenlands, in eastern England are a naturally marshy region supporting a rich ecology and numerous species. Most of the fens were drained centuries ago, resulting in a flat, dry, low-lying agricultural region supported by a system of drainage channels and man-made rivers (dykes and drains) and automated pumping stations. There have been unintended consequences to this reclamation, as the land level has continued to sink and the dykes have been built higher to protect it from flooding.
Fen is the local term for an individual area of marshland or former marshland. It also designates the type of marsh typical of the area, which has neutral or alkaline water and relatively large quantities of dissolved minerals, but few other plant nutrients.
The Fens are a National Character Area,  based on their landscape, biodiversity, geodiversity and economic activity.
The Fens lie inland of the Wash, and are an area of nearly 1,500 sq mi (3,900 km2) in Lincolnshire, Cambridgeshire, and Norfolk. 
Most of the Fens lie within a few metres of sea level. As with similar areas in the Netherlands, much of the Fenland originally consisted of fresh- or salt-water wetlands. These have been artificially drained and continue to be protected from floods by drainage banks and pumps. With the support of this drainage system, the Fenland has become a major arable agricultural region for grains and vegetables. The Fens are particularly fertile, containing around half of the grade 1 agricultural land in England. 
The Fens have been referred to as the "Holy Land of the English" because of the former monasteries, now churches and cathedrals, of Crowland, Ely, Peterborough, Ramsey and Thorney. Other significant settlements in the Fens include Boston, Downham Market, March, Spalding, and Wisbech.  
The Fens are very low-lying compared with the chalk and limestone uplands that surround them – in most places no more than 10 metres (33 ft) above sea level. As a result of drainage and the subsequent shrinkage of the peat fens, many parts of the Fens now lie below mean sea level. Although one writer in the 17th century described the Fenland as entirely above sea level (in contrast to the Netherlands),  the area now includes the lowest land in the United Kingdom. Holme Fen in Cambridgeshire, is around 2.75 metres (9 ft 0 in) below sea level.  Within the Fens are a few hills, which have historically been called "islands", as they remained dry when the low-lying fens around them were flooded. The largest of the fen-islands was the 23-square-mile (60 km2) Kimmeridge Clay island, on which the cathedral city of Ely was built: its highest point is 39 metres (128 ft) above mean sea level. 
Without artificial drainage and flood protection, the Fens would be liable to periodic flooding, particularly in winter due to the heavy load of water flowing down from the uplands and overflowing the rivers. Some areas of the Fens were once permanently flooded, creating lakes or meres , while others were flooded only during periods of high water. In the pre-modern period, arable farming was limited to the higher areas of the surrounding uplands, the fen islands, and the so-called "Townlands", an arch of silt ground around the Wash, where the towns had their arable fields. Though these lands were lower than the peat fens before the peat shrinkage began, the more stable silt soils were reclaimed by medieval farmers and embanked against any floods coming down from the peat areas or from the sea. The rest of the Fenland was dedicated to pastoral farming, fishing, fowling, and the harvesting of reeds or sedge for thatch. In this way, the medieval and early modern Fens stood in contrast to the rest of England, which was primarily an arable agricultural region.
Since the advent of modern drainage in the 19th and 20th centuries, the Fens have been radically transformed. Today arable farming has almost entirely replaced pastoral. The economy of the Fens is heavily invested in the production of crops such as grains, vegetables, and some cash crops such as rapeseed and canola.
Drainage in the Fenland consists of both river drainage and internal drainage of the land between the rivers. The internal drainage was organised by levels or districts, each of which includes the fen parts of one or several parishes. The details of the organisation vary with the history of their development, but the areas include:
The above were all redrained at one time or another after the Civil War (1642–1649).
These were drained in the 18th and 19th centuries. 
At the end of the most recent glacial period, known in Britain as the Devensian, ten thousand years ago, Britain and continental Europe were joined by the ridge between Friesland and Norfolk. The topography of the bed of the North Sea indicates that the rivers of the southern part of eastern England flowed into the Rhine, thence through the English Channel. From the Fens northward along the modern coast, the drainage flowed into the northern North Sea basin. As the ice melted, the rising sea level drowned the lower lands, leading ultimately to the present coastline. 
These rising sea levels flooded the previously inland woodland of the Fenland basin; over the next few thousand years both saltwater and freshwater wetlands developed as a result. Silt and clay soils were deposited by marine floods in the saltwater areas and along the beds of tidal rivers, while organic soils, or peats, developed in the freshwater marshes. Fenland water levels peaked in the Iron Age; earlier Bronze and Neolithic settlements were covered by peat deposits, and have only recently been found after periods of extensive droughts revealed them.  During the Roman period, water levels fell once again. Settlements developed on the new silt soils deposited near the coast. Though water levels rose once again in the early medieval period, by this time artificial banks protected the coastal settlements and the interior from further deposits of marine silts. Peats continued to develop in the freshwater wetlands of the interior fens. 
The wetlands of the fens have historically included:
Major areas for settlement were:
In general, of the three principal soil types found in the Fenland today, the mineral-based silt resulted from the energetic marine environment of the creeks, the clay was deposited in tidal mud-flats and salt-marsh, while the peat grew in the fen and bog. The peat produces black soils, which are directly comparable to the American muck soils. A roddon, the dried raised bed of a watercourse, is more suitable for building than the less stable peat.
Since the 19th century, all of the acid peat in the Fens has disappeared. Drying and wastage of peats has greatly reduced the depth of the alkaline peat soils and reduced the overall elevation of large areas of the peat fens. It is also recorded that peat was dug out of the East and West Lincolnshire fens in the 14th century and used to fire the salterns of Wrangle and Friskney. In later centuries it was used locally for winter fuel and its digging controlled by the Duchy of Lancaster. 
Written records of earthquakes in the Fen area appear as early as 1048. According to Historia Ingulfi, p. 64, (1684)  this took place in Lincolnshire. In 1117 one affected Holland, Lincs, "endangering and injuring Crowland Abbey".  In 1185 Lincoln was damaged.  In 1448 a shock was recorded in south Lincolnshire (Ingulfi, p. 526). In 1750 John Moore records a severe shock attended by a rumbling noise in Bourn after midday. This was felt in Lincolnshire, Leicestershire and Northamptonshire. Houses tottered, slates, tiles and some chimneys fell. As it was a Sunday, some people ran out of the churches "in great consternation".  In 1792 another shock was also felt in Bourne and neighbouring towns.  
There is evidence of human settlement near the Fens from the Mesolithic on.  The evidence suggests that Mesolithic settlement in Cambridgeshire was particularly along the fen edges and on the low islands within the fens, to take advantage of the hunting and fishing opportunities of the wetlands.  Internationally important sites include Flag Fen and Must Farm quarry Bronze Age settlement and Stonea Camp.
The Romans constructed the Fen Causeway, a road across the Fens to link what later became East Anglia with what later became central England; it runs between Denver and Peterborough. They also linked Cambridge and Ely. Generally, their road system avoided the Fens, except for minor roads designed for exporting the products of the region, especially salt, beef and leather. Sheep were probably raised on the higher ground of the Townlands and fen islands, then as in the early 19th century. There may have been some drainage efforts during the Roman period, including the Car Dyke along the western edge of the Fenland between Peterborough and Lincolnshire, but most canals were constructed for transportation. 
How far seaward the Roman settlement extended is unclear owing to the deposits laid down above them during later floods.
The early post-Roman settlements were made on the Townlands. It is clear that there was some prosperity there, particularly where rivers permitted access to the upland beyond the fen. Such places were Wisbech, Spalding, Swineshead and Boston. All the Townlands parishes were laid out as elongated strips, to provide access to the products of fen, marsh and sea. On the fen edge, parishes are similarly elongated to provide access to both upland and fen. The townships are therefore often nearer to each other than they are to the distant farms in their own parishes.
After the end of Roman Britain, there is a break in written records. It is thought that some Iceni may have moved west into the Fens to avoid the Angles, who were migrating across the North Sea from Angeln (modern Schleswig) and settling what would become East Anglia. Surrounded by water and marshes, the Fens provided a safe area that was easily defended and not particularly desirable to invading Anglo-Saxons.
It has been proposed that the names of West Walton, Walsoken and Walpole suggest the native British population, with the Wal- coming from the Old English walh, meaning "foreigner".  However, the villages are in close proximity to the old Roman sea wall, so the wal- element is more probably from wal or weal, meaning "wall". Walton is generally believed to mean "wall-town",  Walsoken to mean "the district under particular jurisdiction by the wall",  and Walpole to mean simply "wall-pole" (Old English wal and pal). 
When written records resume in Anglo-Saxon England, the names of a number of peoples of the Fens are recorded in the Tribal Hidage and Christian histories. They include North Gyrwe (Peterborough and Crowland), South Gyrwe (Ely), the Spalda (Spalding), and Bilmingas (part of south Lincolnshire).
In the early Christian period of Anglo-Saxon England, a number of Christians sought the isolation that could be found in the wilderness of the Fens. Later classified as saints, often with close royal links, they include Guthlac, Etheldreda, Pega, and Wendreda. Hermitages on the islands became centres of communities which later developed as monasteries with massive estates. In the Life of Saint Guthlac , a biography of the East Anglian hermit who lived in the Fens during the early 8th century, Saint Guthlac was described as attacked on several occasions by people he believed were Britons, who were then living in the Fens. However, Bertram Colgrave, in the introduction to one edition, doubts this account, because of the lack of evidence of British survival in the region. British place names in the area are "very few". 
Monastic life was disrupted by Danish (Anglo-Saxon) raids and centuries of settlement from the 6th century but was revived in the mid-10th-century monastic revival. In the 11th century, the whole area was incorporated into a united Anglo-Saxon England. The Fens remained a place of refuge and intrigue. It was here that Alfred Aetheling was brought to be murdered and here where Hereward the Wake based his insurgency against Norman England.
Fenland monastic houses include the so-called Fen Five (Ely Cathedral Priory, Thorney Abbey, Croyland Abbey, Ramsey Abbey and Peterborough Abbey)  as well as Spalding Priory. As major landowners, the monasteries played a significant part in the early efforts at drainage of the Fens.
During most of the 12th century and the early 13th century, the south Lincolnshire fens were afforested. The area was enclosed by a line from Spalding, along the River Welland to Market Deeping, then along the Car Dyke to Dowsby and across the fens to the Welland. It was deforested in the early 13th century. There is little agreement as to the exact dates of the establishment and demise of the forest, but it seems likely that the deforestation was connected with the Magna Carta or one of its early 13th-century restatements, though it may have been as late as 1240. The forest would have affected the economies of the townships around it and it appears that the present Bourne Eau was constructed at the time of the deforestation, as the town seems to have joined in the general prosperity by about 1280.
Though the forest was about half in Holland (Lincolnshire) and half in Kesteven, it is known as Kesteven Forest. 
Though some signs of Roman hydraulics survive, and there were also some medieval drainage works, land drainage was begun in earnest during the 1630s by the various investors who had contracts with King Charles I to do so.  The leader of one of these syndicates was the Earl of Bedford, who employed Cornelius Vermuyden as engineer. Contrary to popular belief, Vermuyden was not involved with the draining of the Great Fen in Cambridgeshire and Norfolk in the 1630s, but only became involved with the second phase of construction in the 1650s.  The scheme was imposed despite huge opposition from locals who were losing their livelihoods based on fishing and wildfowling. Fenmen known as the Fen Tigers tried to sabotage the drainage efforts.
Two cuts were made in the Cambridgeshire Fens to join the River Great Ouse to the sea at King's Lynn – the Old Bedford River and the New Bedford River, the latter being known also as the Hundred Foot Drain. Both cuts were named after the Fourth Earl of Bedford who, along with some gentlemen adventurers (venture capitalists), funded the construction and were rewarded with large grants of the resulting farmland. The work was directed by engineers from the Low Countries. Following this initial drainage, the Fens were still extremely susceptible to flooding, so windpumps were used to pump water away from affected areas. The Company of Adventurers were more formally incorporated in 1663 as the Bedford Level Corporation.
However, their success was short-lived. Once drained of water, the peat shrank, and the fields lowered further. The more effectively they were drained, the worse the problem became, and soon the fields were lower than the surrounding rivers. By the end of the 17th century, the land was under water once again.
Though the three Bedford Levels together formed the biggest scheme, they were not the only ones. Lord Lindsey and his partner Sir William Killigrew had the Lindsey Level inhabited by farmers by 1638, but the onset of the Civil War permitted the destruction of the works until the 1765 Act of Parliament that led to the formation of the Black Sluice Commissioners. 
Many original records of the Bedford Level Corporation, including maps of the Levels, are now held by Cambridgeshire Archives and Local Studies Service at the County Record Office in Cambridge.
The major part of the draining of the Fens was effected in the late 18th and early 19th century, again involving fierce local rioting and sabotage of the works. The final success came in the 1820s when windpumps were replaced with powerful coal-powered steam engines, such as Stretham Old Engine, which were themselves replaced with diesel-powered pumps, such as those at Prickwillow Museum and, following World War II, the small electric stations that are still used today.
The dead vegetation of the peat remained undecayed because it was deprived of air (the peat being anaerobic). When it was drained, the oxygen of the air reached it, since then the peat has been slowly oxidizing.  This, together with the shrinkage on its initial drying and the removal of soil by the wind, has meant that much of the Fens lies below high tide level. As the highest parts of the drained fen are now only a few metres above mean sea level, only sizeable embankments of the rivers, and general flood defences, stop the land from being inundated. Nonetheless, these works are now much more effective than they were.
The Fens today are protected by 60 miles (97 km) of embankments defending against the sea and 96 miles (154 km) of river embankments. Eleven internal drainage board (IDB) groups maintain 286 pumping stations and 3,800 miles (6,100 km) of watercourses, with the combined capacity to pump 16,500 Olympic-size swimming pools in a 24-hour period or to empty Rutland Water in 3 days. 
As of 2008, there are estimated to be 4,000 farms in the Fens involved in agriculture and horticulture, including arable, livestock, poultry, dairy, orchards, vegetables and ornamental plants and flowers. They employ about 27,000 people in full-time and seasonal jobs. In turn, they support around 250 businesses involved in food and drink manufacturing and distribution, employing around 17,500 people. 
Over 70% of the Fens is involved in environmental stewardship schemes, under which 270 miles (430 km) of hedgerow and 1,780 miles (2,860 km) of ditches are managed, providing large wildlife corridors and habitat for endangered animals such as the water vole. 
In 2003, the Great Fen Project was initiated to return parts of the Fens to their original pre-agricultural state. The periodic flooding by the North Sea, which renewed the character of the Fenlands, was characterised conventionally by the 1911 Encyclopædia Britannica as "ravaged by serious inundations of the sea". The modern approach is to allow a little farmland to be flooded again and turned into nature reserves. By introducing fresh water, the organisers of the project hope to encourage species such as the snipe, lapwing and bittern. Endangered species such as the fen violet will be seeded.
The Fens Waterways Link is a scheme to restore navigation to some of the drainage works. It is planned to bring the South Forty-Foot Drain and parts of the Car Dyke into use as part of a route between Boston and Cambridge.
The Fens is the origin of English bandy and Fen skating. It is the base of Great Britain Bandy Association  and in Littleport there is a project in place aiming at building an indoor stadium for ice sports. If successful, it will have the largest sheet of ice in the country with both a bandy pitch and a speed skating oval. 
Many historic cities, towns and villages have grown up in the fens, sited chiefly on the few areas of raised ground. These include:
Ancient sites include:
This article may be in need of reorganization to comply with Wikipedia's layout guidelines .(March 2022)
Some authors have featured the Fens repeatedly in their work. For example:
The following fictions, or substantial portions of them, are set in the Fens:
Some films have large portions set in the Fenlands:
Video games also have been set in the Fens:
Cambridgeshire is a ceremonial, historic and non-metropolitan county in the East of England government statistical region, and popularly known as one of the three counties of East Anglia. The largest city is Peterborough, followed by the county town of Cambridge.
Crowland or Croyland is a town in the South Holland district of Lincolnshire, England. It is situated between Peterborough and Spalding. Crowland contains two sites of historical interest, Crowland Abbey and Trinity Bridge.
The River Nene is a river in the east of England that rises from three sources in Northamptonshire. The river is about 105 miles (169 km) long, about 3.7 miles (6.0 km) of which forms the border between Cambridgeshire and Norfolk. It is the tenth-longest river in the United Kingdom, and is navigable for 88 miles (142 km), from Northampton to The Wash.
The River Great Ouse is a river in England, the longest of several British rivers called "Ouse". From Syresham in Northamptonshire, the Great Ouse flows through Buckinghamshire, Bedfordshire, Cambridgeshire and Norfolk to drain into the Wash and the North Sea near Kings Lynn. Authorities disagree both on the river's source and its length with one quoting 160 mi (260 km) and another 143 mi (230 km). Mostly flowing north and east, it is the fifth longest river in the United Kingdom. The Great Ouse has been historically important for commercial navigation, and for draining the low-lying region through which it flows; its best-known tributary is the Cam, which runs through Cambridge. Its lower course passes through drained wetlands and fens and has been extensively modified, or channelised, to relieve flooding and provide a better route for barge traffic. The unmodified river would have changed course regularly after floods.
The Old Bedford River is an artificial, partial diversion of the waters of the River Great Ouse in the Fens of Cambridgeshire, England. It was named after the fourth Earl of Bedford who contracted with the local Commission of Sewers to drain the Great Level of the Fens beginning in 1630. It provided a steeper and shorter path for the waters of the Great Ouse, and was embanked to prevent them flooding the low ground of the South Fens. Throughout the project, the Earl and his Adventurers faced disruption from those who were opposed to drainage schemes. The project was deemed to have succeeded in draining the fens in 1637, but that decision was reversed in 1638. After a lull during the English Civil War, when much of the work was damaged, the Dutch engineer Cornelius Vermuyden worked with William Russell, the fifth Earl of Bedford to complete the drainage. Disruption and unrest continued while the work was carried out, resulting in the Adventurers employing armed guards. A second river, the New Bedford River, was cut parallel to the first channel, which then became the Old Bedford River. At some point, the Old Bedford River was split into two parts, when the upper section was diverted into the River Delph at Welches Dam, and the lower section was joined to the Counter Drain. Both parts retain the name, but are not connected to each other. The area between the two Bedford rivers acts as a large washland, which holds floodwater when the river channels cannot cope with the volume of water in them.
The New Bedford River, also known as the Hundred Foot Drain because of the distance between the tops of the two embankments on either side of the river, is a navigable man-made cut-off or by-pass channel of the River Great Ouse in the Fens of Cambridgeshire, England. It provides an almost straight channel between Earith and Denver Sluices. It is tidal, with reverse tidal flow being clearly visible at Welney, some 19 miles (31 km) from the sea.
Ouse Washes is a linear 2,513.6-hectare (6,211-acre) biological Site of Special Scientific Interest stretching from near St Ives in Cambridgeshire to Downham Market in Norfolk. It is also a Ramsar internationally important wetland site, a Special Protection Area for birds, a Special Area of Conservation and a Nature Conservation Review site, Grade I. An area of 186 hectares between March and Ely is managed by the Wildlife Trust for Bedfordshire, Cambridgeshire and Northamptonshire and another area near Chatteris is managed by the Royal Society for the Protection of Birds. The Wildfowl & Wetlands Trust manages another area near Welney.
Spalding is a market town on the River Welland in the South Holland district of Lincolnshire, England. The town had a population of 31,588 at the 2011 census. The town is the administrative centre of the South Holland District. The town is located between the cities of Peterborough and Lincoln, as well as the towns of Bourne, March, Boston, Wisbech, Holbeach and Sleaford.
Sir Cornelius Vermuyden was a Dutch engineer who introduced Dutch land reclamation methods to England.
The Deepings are a series of settlements close to the River Welland near the borders of southern Lincolnshire and north western Cambridgeshire in eastern England. Peterborough is about 8 miles to the south, Spalding about 10 miles to the north east and Stamford about 8 miles to the west.
Thorney is a village in the Peterborough unitary authority in the ceremonial county of Cambridgeshire, England. Located around eight miles (13 km) east of Peterborough city centre, on the A47.
Tydd St Giles is a village in Fenland, Cambridgeshire, England. It is the northernmost village in the Isle of Ely, Cambridgeshire, on the same latitude as Midlands towns such as Loughborough, Leicestershire and Shrewsbury, Shropshire. The village is in the distribution area of one local free newspaper, The Fenland Citizen.
The Middle Level Navigations are a network of waterways in England, primarily used for land drainage, which lie in The Fens between the Rivers Nene and Great Ouse, and between the cities of Peterborough and Cambridge. Most of the area through which they run is at or below sea level, and attempts to protect it from inundation have been carried out since 1480. The Middle Level was given its name by the Dutch Engineer Cornelius Vermuyden in 1642, who subsequently constructed several drainage channels to make the area suitable for agriculture. Water levels were always managed to allow navigation, and Commissioners were established in 1754 to maintain the waterways and collect tolls from commercial traffic.
Cowbit is a village and civil parish in the South Holland district of Lincolnshire, England. The population of the civil parish at the 2011 census was 1,220. It is situated 3 miles (5 km) south from Spalding and 5 miles (8 km) north from Crowland.
Elm is a village and civil parish in the Fenland District of Cambridgeshire, England. In Domesday, it is called Helle.
The Middle Level Commissioners are a land drainage authority in eastern England. The body was formed in 1862, undertaking the main water level management function within the Middle Level following the breakup of the former Bedford Level Corporation.
Outwell is a village and civil parish in the borough of King's Lynn and West Norfolk, in the English county of Norfolk.
The Witham Navigable Drains are located in Lincolnshire, England, and are part of a much larger drainage system managed by the Witham Fourth District Internal Drainage Board. The Witham Fourth District comprises the East Fen and West Fen, to the north of Boston, which together cover an area of 97 square miles (250 km2). In total there are over 438 miles (705 km) of drainage ditches, of which under 60 miles (97 km) are navigable. Navigation is normally only possible in the summer months, as the drains are maintained at a lower level in winter, and are subject to sudden changes in level as a result of their primary drainage function, which can leave boats stranded. Access to the drains is from the River Witham at Anton's Gowt Lock.
A roddon, also written as rodham, roddam or rodden, is the dried raised bed of a watercourse such as a river or tidal-creek, especially in The Fens in eastern England. Such raised silt and clay-filled beds are ideal for settlement in the less firm peat of The Fens. Many writers have followed the archaeologist Major Gordon Fowler's preference for the word roddon to define such structures though modern researchers suggest the word rodham is the more correct local word.
The Bedford Level Corporation was founded in England in 1663 to manage the draining of the Fens of East Central England. It formalised the legal status of the Company of Adventurers previously formed by the Duke of Bedford to reclaim 95,000 acres of the Bedford Level.