The Vikings - The Ring Castles in Denmark

1) Trelleborg

Trelleborg house, photo: grethe bachmann 2004

A special class of monuments from the Viking Age are four ring castles or military camps in Denmark  The earliest found is Trelleborg at Sjælland (Zealand). It lies in the western part of Sjælland ab. 4 km west of the town Slagelse, between this and Storebælt, where two rivers meet - and from here they are running as one river out into the sea north of the town Korsør. The Viking ring castles are colloquially known as "Trelleborge". The ring castle Trelleborg at Sjælland was placed upon the land between two rivers in the late Viking period, the excavations showed that it probably was built upon an ancient blót-place, which was seen from several sacrifice pits and from some house-rests. After comprehensive fill- and levelling work the castle was built, according to a thoroughly worked-out  project, which by skilled engineers were laid out in the field with extraordinary mathematical precision. The ring castle consisted of two components: a main castle and a front castle.

map from wikipedia

The main castle is a circular place, surrounded by a strong and still existing ring bank, which towards the land side (south and east) is further strengthened by a curved broad and deep moat. This ring bank had four gates, one to each corner of the world, and these gates were interconnected  two and two (crosslike) with wooden streets crossing in the center of the place and dividing it in four equal sized sections. In each section were 4 equal size houses, arranged in blocks, a total of 16 houses. With their curved long walls and their straight cut ends these houses looked like ships with cut bows. Each house was divided in 3 rooms, one smaller in each end and a large mid-room, 18 meter long. The planks of the houses have disappeared, but have left marks in the earth in several places, which show the plan and the contour of the buildings.

A few lesser houses were noticed, partly guard houses at two gates, partly chief houses in the middle of two blocks, and finally a ship-shaped house in smaller dimensions north of the northeastern block. It seems furthermore that inside, along the ring bank, was a ring street. The ring bank had palisades on both sides and was in several places strengthened with an inside timber reinforcement. The 4 gates, which behind the palisades had strong stone packings, were covered by a timber loft and worked as tunnels. Outside they could be closed by a couple of gate wings (iron rings and big keys were found by the entrances). Outside, towards the landside, the ring bank was dressed with a mantle of stiff clay, held together by wooden sticks and branches. Towards the meadows, to the northwest and southwest, the bank rested upon a foot of stone and post work and was higher up covered by vertical palisades.

Trelleborg, the castle site, wikipedia

The second component of the castle was a reinforcement belt towards the landside = a front castle. This belt, which was curved to the south like the curve of the main castle, but square to the north, was fortificated with a low bank and a flat moat. Upon the curved section was built in a radial construction: total 13 elliptic longhouses in the same shape as the 16 block houses of the main castle, but of a little smaller size. Upon the square section of the belt were near the castle (outside its eastern gate)  two similar houses placed parallelly; and further to the east was the castle's burial site with ab. 150 graves, probably  following the ancient sacrifice place, which before Trelleborg's building belonged to the sacrifice place out on the isthmus. The  entrance to main castle and front castle were both from the south.

Trelleborg, photo H. Stiesdal 1948/ Johannes Brøndsted, Vikingerne, Gyldendal 1960  

An impressive  plan like Trelleborg was made by engineers. The used unit of measure is an approximated Roman foot (Roman normal foot: 29,57 cm - the calculated medium size of the Trelleborg foot is 29.33 cm ), which is shown in all the main measures of the castle. The block houses are 100 feet long, the front castle houses 90 feet, the ring bank is 60 feet broad, the small houses in the middle of the two blocks are 30 x 15 feet. Radius from the center to the inner edge of the ring bank is 234 feet, the distance between the two moats is also 234 feet, while the distance from the center to the nearest gables of the front castle houses has the double measure = 468 feet. In the construction the center was chosen first, from where the circular curves were marked which limit the banks and moats; the same center is also the cutting point of the two mutually perpendicular main axis, which divide the main castle area in four equal large sections, which continue through the four gates. All over the constructors have used extremely care and precision.The whole building plan inside the ring is constructed in squares.

 Example of house at Fyrkat/ photo grethe bachmann

Example of house at Fyrkat: photo: grethe bachmann 2010


Trelleborg has a splendid location in the large meadows with its back to the higher mainland. The holes in the underground from the houses are marked in the grass by cement -  the ring banks and the moats are partly rebuilt, and the visitors will get a stunning impression of how a Viking garrison looked in the Viking period. The National Museum has constructed a modelhouse in full size, it's like one of the front castle houses. It was  placed upon the site in a short distance from the castle. The modelhouse is built in wand construction with walls of broad vertical planks. The roof is constructed above cross beams where stand vertical short posts, it has a length-curved ridge and is thatched with wood chippings. Outside along the longwalls run a low gallery with its own roof; its purpose might have been to guard the longwall against rain and snow. A house had usually door in both gables and in both cross walls, and there were two side-doors in the long mid-room, one placed in each longside and always counterposed diagonally. The gable rooms had sometimes digged cellars ( maybe storerooms for food or waste pits or even dungeons). In the large mid-room was a plank or clay floor and a fireplace in the middle, and at the sides were probably broad sitting- and lying benches. In the roof probably an air hole (a lyre). The Trelleborg house is like this description. It is not certain and can never be if this house is exactly like it  really was. The construction has been critizised and there have been suggestions about other Trelleborg houses. The Fyrkat houses can tell us more ( see the coming article about Fyrkat). The Trelleborg house was renovated in the 1980s.

Trelleborg, common burial, photo 1948 NN/ Johannes Brøndsted, Vikingerne, Gyldendal 1960.  


The burial site of Trelleborg tells us as expected that the main part of the buried were young or younger men (20-40 years); but there were also several women, a few children and some old people. The gifts in the graves were relatively few. Nothing indicates Christianity, unburnt burials with the body placed east-west were known in Denmark before Christianity arrived and marked the burial customs. Three graves were common graves, the largest with ten burials. The grave gifts included only few weapons ( most remarkable was an unusually  broad-edged, but also narrow-bladed silverplated war axe ) - there were several tools, like blacksmith tools and agricultural tools (scythe blades and a ploughshare). And furthermore jewelry, claypots and things for spinning and weaving. These things give Trelleborg a safe dating: namely to the last part of the 10th century and the first half of the 11th  (ab. 975-1050). The life of the castle was not long, but obviously it did exist, when Sven Tveskæg conquered England and when Cnut the Great fought the Three King Battle at Helgeaa.

 Trelleborg, silverchain with Thor-hammer, Danish/ Johannes Brøndsted, Vikingerne, Gyldendal 1960.


It is also obvious that Trelleborg was a military camp and a naval base. The location is classic with an easy access to the sea and however with protection and shelter from assault and floods. Ship could supposedly be trailed up the river stream to the castle, and each ship-shaped blockhouse housed a ship's crew. The contents of the graves (as for agricultural tools) indicate that the people of the castle had to provide supplies so they did not have to rob the farmers from the neighbourhood.

Trelleborg gives witness about a strong organizing power. This can only be a king, who was able to build such great plans. There are no supporting points, which indicate that a hostile power was stuck in Denmark. The archeaological finds do not tell about this -  and not history either. But history tells another story: that this period was marked by a Danish display of power. Trelleborg had room for 1200 men. It is not known when the Trelleborg camp went out of use. There are no traces after a finishing fire.

Text/translated: grethe bachmann 
Source Johannes Brøndsted, Vikingerne,Gyldendal 1960. 
 Next:  Aggersborg, Fyrkat, Nonnebakken. 

Information from Slagelse Municipality 2013:
Trelleborg is a fantastic piece of cultural heritage from the Viking period and the best and best preserved of the three circular castles Fyrkat, Trelleborg and Aggersborg. Together with among fx the Jelling monuments and Dannevirke the ring castles tell us about a very exiting and crucial time in Danish an European history.
The location Trelleborg was never forgotten, the main part of the earth banks were directly visible right up to the beginning of the excavation - and the circular inner bank is seen clearly upon maps from the 1600s and onward, but the character of the installations was first known as a Viking fortification when the National Museum started the excavations in 1934 under the leadership of archaeolog Poul Nørlund.  The excavation was provoked by a local motorcycle club who had rented the area in 1933 for the purpose of converting it into a motocross track.   
(Source:  Slagelse Kommunes hjemmeside. )




Other Informations (Source: wikipedia):

Trelleborg was the first discovery of a circular castle in Denmark.
 
The Trelleborg area is about 6 ha = 12 football fields. F

The excavation, the registration of findings and the reconstruction of building works were published in 1948 in a scientific paper written by Poul Nørlund. 

In 1979 it was succeeded to do a dendrochronological dating of wooden pieces from Trelleborg, and it was detected that the trees were felled in June or July 980.

For the building of Trelleborg was felled half of the oak woods which existed at Sjælland.


Already in Poul Nørlund's paper the building master was identified as either Harald Blåtand or Sven Tveskæg, mostly all scholars,who have commented this question, agree that it must be the same person, who was the building master of these castles. One of the essential arguments is the precise geometry in the main line of the plan and the common characteristics in the craftmanship. Another argument is the great  similarities in the design of the plans. The dendrochronological datings from Trelleborg points at Harald Blåtand as the building master and because of the dating the historians now mostly agree to point at Harald.

There are no written sources which mention the ring castles in a direct way. The known Scriptures close to the events are the chronicle by bishop Thietmar of Merseburg, written 1013-18, and an unnamed monk of St. Omer's tribute to Cnut the Great's widow, written about 1040. Here is a possible reference to the Trelleborgs, since it is told that Sven Tveskæg fortified his kingdom with castles, which had to be a protection against the enemies who had invaded and occupied the country.

Adam of Bremen's work from ab. 1070, descriptio insularum Aquilonis, illustrated a number of factors related to the Danish Viking period , but there has not been identified any mention of the ring castles. The Danish chronicles from the Middle Ages (Aggesen and Saxo) have no direct references either. It is remarkable that the ring castles are not mentioned, and it seems that the writers did not know the existence of the castles - and this is an indirect evidence of the short lifetime of these castles.


Latest info: 

Wooden shield from Trelleborg, exhibition Moesgård Museum Århus

In September 2008 archaeologists from Sydvestsjællands Museum and from Moesgård Museum (Århus) found a wooden shield during an excavation at Trelleborg. It is the first time a wooden shield was found in Denmark. The shield is about 80 cm diameter with a characteristic hole in the middle for the shield boss. The shield is dated to the Viking period and to the castle's usage period in the end of the 900s.

Anders Dorset, one of the leading archaeologist at the excavations, also considers that the examination shows evidence of that Trelleborg had a clear maritime significance.