Anglo-Saxon hydraulic engineering in the Fens

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Anglo-Saxon hydraulic engineering in the Fens

March 11 @ 5:00 pm - 6:00 pm


Anglo-Saxon hydraulic engineering in the Fens

by Prof. Michael Chisholm FSA

For the Fens south of the Wash, it has long been held that only the Romans or the Normans were capable of major hydraulic engineering.  Much has been done in recent decades challenging this view but the full significance of a major Anglo-Saxon example has not hitherto been recognised.

Three channels marking the northern boundary of Cambridgeshire formed a distributary of the Nene from Peterborough to the Wash in post-Conquest times.  It used to be thought that because county boundaries were established in late Anglo-Saxon times they were natural in origin but they were in fact artificial – Cat’s Water, (Old) South Eau and Shire Drain.  Two ‘appendicies’, respectively connected to Crowland (river Welland) and to Guyhirn (and the outfall of the Ouse and Nene at Wisbech).  The five artificial channels, amounting to 27 miles, can individually be shown to be artificial.  They are interdependent, with Cat’s Water converted from a locally originating minor stream to a flowing distributary of the Nene. All but Shire Drain were fully navigable by barges.  Post-Conquest evidence shows channels up to 40 feet wide. There must have been some degree of overall concept and agreement about their construction.

There is no evidence that the works were Roman.  Therefore, attention must focus upon the Benedictine Fenland monasteries founded or re-founded about 970 – Crowland, Ely, Peterborough, Ramsey and Thorney.  The abbey at Ely in the late tenth century had control of most, if not all, of the land on the Cambridgeshire side of Cat’s Water etc.  On the other side, Peterborough and Crowland abbeys controlled lands along the whole length.  Crowland controlled land adjacent to some of (Old) South Eau; the remainder of the Lincolnshire side was controlled by a handful of rich lay persons.  The channels must have been created in the last quarter of the tenth century or early in the eleventh.  There must have been some form of agreement between abbeys.  Ely and Peterborough were two of the richest monasteries in England at Domesday.


  1. The Anglo-Saxons were more capable hydraulic engineers than has hitherto been realised.
  2. Under king Edgar, and perhaps for a while thereafter, promotion of the Benedictine doctrine should be seen as an important part of statecraft for cementing the English kingdom.
  3. In important respects, the Benedictine monasteries should be considered as acting as agents of the Crown.
  4. There would have been a particular geo-political reason to ensure control and development of the Fens, since the rivers Welland and Great Ouse provided easy ingress for foreign invaders; Vikings had reached to Stamford and to Bedford.
  5. The conventional narrative about water management in the Fens needs to be revised:
  6. Large-scale concept and action occurred in the tenth century, several centuries earlier than is conventionally realised.
  7. The dual function of channels in the silt fens and along the margins thereof needs to be recognised.  Creation of a navigable channel where there is only a thin layer of peat would yield solid spoil from which to create an embankment that would protect land from floods and facilitate water management for pasture if not for arable use.

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March 11
5:00 pm - 6:00 pm
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