Sheep Taking Shelter in the latest storms

Grote Mandrenke

Huge storms and devastating floods are not something new. Medieval history shows that human overexploitation and not the climate may be behind many tragedies

At the start of the little Ice Age, the North sea was hit by a series of storm tides. One of the most infamous was “Das Grote Mandrenke” in 1362 – the great drowner of men. However, not only the changing weather conditions caused the hight floods post 1300. Changing patterns of explotation of the marshy regions along the coastline from Denmark to Holland caused the catastrophies. It began on the 15th of January 1362 but reached its high point on the 16th. This flood caused the destruction of a series of outlying promontories on the Western Coast of Jutland and Friesland all the way down to Holland.


Rungholt and the Halligen 1650 AD
Rungholt and the Halligen 1650 AD

One victim was the city of Rungholt, which until the beginning of the 20th century used to yield medieval artefacts and debris into the nets of fishermen. During the storm it sank beneath the waves, while the isle of Strand was created. Surveys conducted in the 20s and 30s, when remains of the city were suddenly exposed, suggest a large population of about 1500 – 2000 persons. It is likely that Rungholt was a major port shipping cattle to the markets in Holland and Flandern. There are no contemporary descriptions of Das Grote Mandrenke and later estimates of the number of deaths were probably highly exaggerated. However, there is no doubt that its memory lingered for a long time. Local myth still has it than whenever a storm brews in the Wadden Sea and the region is threatened with a flood, people sailing through might still hear the bells ringing.

All Saints

Waterlevel inside Ribe Cathedral after storm 1656
Waterlevel inside Ribe Cathedral after storm 1656

Thus in 1436 the first flood of “All Saints” hit the coast, which caused the Cathedral of Schleswig to apply for help in Basel, which at that time housed the Concilium Basiliense. The argument was that 60 parishes had been lost to the sea. Yet again in 1532 the second “Storm of All Saints” hit with a vengeance. Several thousand people perished. In the city of Tønder in Southern Jutland, where water stood 5,3 meters above the mean sea level, it reached 1,8 meter up from the floor in the aisle of the church of St. Laurentius. In Ribe, a nearby city, it was possible to catch fish in the cloister of the cathedral. According to the mark in the Cathedral of Ribe, the worst was still to come. In December 1634 the sea reached 5.5 meters above the usual and water stood 1,6 meters above the floor in the Cathedral (as witnessed by a mark cut into the wall of the church.) A chronicler, Peter Sax, wrote that “at seven o’clock the Lord turned the wind into South West and let it storm so fiercely, that no human being could walk nor stand. Between 8 and 9 all dykes were broken and eroded. The air was full of fire, the heaven burned and the Lord let all thunder, hailstorms and lightening loose while the wind blew with such a strength that the earth moved.” At this storm the island of Strand was once more broken into fragments out of which were created the islets of Pellworm, Nordstrand and Nordstrandischmoor. Two thirds of the population on Strand died during that storm.

Houses on warfts

Land Unten - The Church Yard at Hallig Hoog 1981
Land Unten – The Church Yard at Hallig Hoog 1981 Photo taken on the morning of the storm by the local vicar

Early on people tried to defend themselves against the tidal storms by building their farms or villages on warfts or highly silted banks – artificial mounds. The salt marshes of Ditmarschen were already settled during 1st century AD. Archaeological excavations have pointed out the existence of such warfts with longhouses bordering a channel at Süderbusenwurth. Larger warfts existed along the estuary of the River Eider. The economy of these settlements was based on husbandry with cattle grazing on the salt marshes. Only small-scale farming has been demonstrated with plants like horse beans, barley, oats, emmer and flax. The crops were grown in garden-plots on higher banks during summer. At some point between 400-600 these settlements were left; perhaps the inhabitants took part in the Anglo-Saxon migration to England in this period or they joined up with the other German-speaking neighbours on their waytowards the South (the Langobardians e.g.) . Later the area was once more inhabited.The best example of an early medieval warft is at Wellinghusen near Wöhrden. Here a settlement was established at the end of the 7th century AD. Later at the beginning of the 9th century new housing was erected on separate mounds. Later a larger village mound was developed; this was continuously raised until the 14th century AD. Nowadays the inhabitants on a number of small islands in the North Sea, the Halligen, still depend on such warfts to carry them through stormy weather. Here the traditional way of life may be still be experienced.

Dikes and drainage

In the 11th century the building of dikes and the drainage of land began. Initially the dikes were built around the arable fields to keep out the occasional spring or summer floods. (The winter floods were heavier but also left precious silt, which fertilised the fields promising the large yields known from a later period.) Later, in the 13th century, some of these ring-dikes were connected and raised by cooperatives, called Geschlechter (literally “kinships”) in Ditmarschen. These dikes were however a blessing in disguise. As the foreland with its tidal flats were reduced, winter flooding became heavier demanding yet higher dykes to be built. At the same time the peat was systematically cut off and used in salt-production, reducing the natural defence mechanisms of the landscape. It was this overexploitation as much as the changing climate, which caused the terrible storms in The Little Ice Age.


Medieval Histories, 2012: 11:1


Schleswig-Holstein im Frühen Mittelalter. Landschaft, Archäologie, Geschichte. By Dirk Meier Boyens Verlag 2011 ISBN: 978-3-8042-1341-8

Dike Building, Storm Surges and Land Losses at the North-Sea coast of Schleswig-Holstein, Germany By Dirk Meier (For anyone reading German this is a treasure throve of articles and papers about the early medieval life-world in the Wadden Sea.)

Stom 1981 At the Wadden See