| The Trelleborg Fortresses
| | The first real castles known in Scandinavia, besides the so-called peasant castles, are Harald Blueetoth circular castles called the Trelleborge. These castles were important instruments in the military machine, which the king created in order to conquer the Danish territories. It is still widely discussed where he king had his ideas for these fortifications.
However, one probable theory is that the king through marriage obtained the Obrodites, a Slavonic people as an ally in his Nordic power struggle. |
Trelleborg Fortresses in General
In Denmark there are remnants of the four so-called ” trelleborg fortresses”. The fortresses have had a very uniform and strictly geometrical structure. The fortress type had a circular rampart with gates facing the four corners of the world. Two crossing roads have gone through the fortress and the uniform long houses are grouped in four-winged yard formations along the main roads. Close to the gates there was a church.
Earlier they thought that these fortresses had been built by the Viking King Sweyn Forkbeard and had functioned as training camps for the forces, which were sent to England. However, by way of year ring dating we have been able to prove that the fortresses have entered into the unification of the kingdom, which Sweyn Forkbeard´s father Harald Bluetooth carried through in the 970´s.
The best preserved ring fortress is Trelleborg in Zealand. 16 long houses have been found inside the ramparts and 15 in fan-shape just outside. 157 Christian graves have been found outside one of the gates and mark the place of the wooden church. Year ring dating shows that the fortress has been built around the years 975-978.
In Funen there was a trelleborg fortress in Odense. All traces above the ground has disappeared now entirely. However, excavations have been made in the moat outside the fortress. A piece of wood has been dated to just after 980. There is a church close to the fortress.
The ring fortress Fyrkatis situated app. 70 kilometres north of Aarhus in Northern Jutland. 16 long houses have formed four groups of farms inside the ramparts. Via year ring dating the time of the construction established to the middle or the end of the 970`s. Remnants of a church outside of the ramparts have not been found, and there have been any archaeological excavations in the area.
Aggersborg at the north coast of Limfjorden is the larges of all the trelleborg fortresses. The diameter is an impressive 240 metres. Inside the ramparts there were no less than 48 long houses in 12 large, square groups. Just outside the northern gate the stone church from the early Middle Ages remains. It substituted the wooden church, which must have been built here by Harald Bluetooth.
Trelleborg | 
Reconstruction Slagelse | 
Fyrkat | 
Reconstruction of Fyrkat | 
The Design of the Trelleborgs |
Trelleborg
In the middle of the medieval town Trelleborg at Scania´s south coast well-preserved remnants of the trelleborg fortress, which gave the present town its name, has been found. The lower parts of the ramparts and the dry moats, which are situated outside the ramparts, could be seen along the western quadrant, while smaller excavations towards east and south revealed the total size.
Contrary to the Danish fortresses, Trelleborg´s fortress has not been circular, but the deviance from the circular shape is minimal. Another special feature is, that they haven´t found upright holes from building activity inside the fortress area. As the rampart has been added later, there must have been long houses there. Very likely they have been of a type, which do not leave any traces, for instance because the walls have rested on a wooden foundation above ground.
A no wooden objects have been preserved; it has not been possible to make a year ring dating. However, with the so-called C14 technology the time has been established to be around the 970`s.
Trelleborg in Scania | 
Trelleborg´s rampart. |
Borgeby
Borgeby is situated by Lødde River a few kilometres from the Sound coast. Just north of the small river is the large trading place from the Viking Age at Løddekøpinge. The terrain slopes steeply towards the river and on top of the flat hill, Harald Bluetooth has built one of his ring fortresses, the so-called trelleborg.
Remnants of the ring fortress´ ramparts are still there, but they have been heavily ploughed down. Via excavations it has been established that the fortress has had two building phases. The first ring rampart is comparatively narrow. Outside the rampart there was a moat without water. After some time the rampart has been enlarged with earth. The earth has been taken from an extension of the moat, which thus became deeper and broader.
At an excavation in 1993 they found remnants of a goldsmith´s workshop. The workshop seems to have been in use by the end of the 10th century. The jewellery, which was made here was fine and in a design only used by magnates, probably those, who were close to Harald Bluetooth. Even though only a very small area has been examined, there are certain proofs that Borgeby in the end of the 10th century was a very important place. Coins from the middle of the 11th century with the place name also indicate that the king struck coins in the fortress
In the 12th century a large square tower was built in the middle of the fortress. At this time the king must have turned over the fortress to the arch bishop in Lund. Today there are still several buildings from the 13th century to the 16th century.
Borgeby |
Are There More Trelleborg fortresses?
In Denmark four so-called trelleborg fortresses have been known for a comparatively long time. In the 1980`s and the 90`s two more were found, one in Borgeby and one in Trelleborg. Even though they both were undoubtedly the trelleborg type, there was some discussion. The Danish trelleborg fortresses have been connected to Harald Bluetooth, i.e. with a part of the Danish national culture.
When the Swedish scholar, Rikard Holmberg, presented his thesis, ”The Sound Coast in the Middle Ages”, in 1977, he put forward facts and hypotheses on a possible trelleborg fortress in Borgeby. The Danish official opponent considered this idea to be completely mad. The trelleborg fortresses only existed east of the Sound. The find of the trelleborg fortress in Trelleborg in the 1980`s the Swedish keeper of national antiquities considered a complete impossibility with the absurd argument that “trelleborg fortresses do not exist in Sweden”.
A Controversial Subject
The subject trelleborg is therefore very sensitive nationally, but that doesn´t rule out that there could have been more than the ones we know now in the area, which Harald Bluetooth conquered: The Swedish scholar Sven Rosborn has re-examined the subject in his book from 2004, ” The Scanian History. The Vikings.” The results are from this book.
Today you can safely say that Harald Bluetooth in the 970`s and 80`s conquered a large part of the area, which later was to become Denmark. The king, through his marriage had allied himself with the powerful Slav people, the Obodrits and he had become a Christian. The Christian touch in the trelleborg fortresses is also evident. Just outside the gates there is always a church or traces in the form of Christian graves.
The Importance of the St. Clemens´ Churches
St. Clemens became very popular in the 10th century, when he became the patron saint of Kiev. In the first period after the introduction of Christianity a small number of churches were built in Scandinavia in order to honour St. Clemens. They were all the personal property of the king. Perhaps Harald Bluetooth indeed had taken Clemens as his patron saint? Many criteria must be satisfied in the hunt for more, not yet unearthed trelleborg fortresses. There must be circular ramparts with a diameter of around 150 metres, two main roads must have crossed the circle and created an opening towards each corner of the world. Just outside these openings, there must have been a church. It must be consecrated for St. Clemens. Which places are possible candidates?
Known and Possible Trelleborgs |
Roskilde
According to the sources Harald Bluetooth may have founded this town, and his body was taken here to be buried. Just opposite the harbour of the Viking Age is St. Clemens´ Church, one of the oldest, best preserved stone churches in Scandinavia. It is from app. 1080, but an earlier church was built here around the year 1030. The area forms a plateau, where a trelleborg fortress may have been situated.
Sct .Clemens Church in Roskilde |
Copenhagen
Ever since the beginning of the 20th century it has been known that a round rampart with a moat in the middle of Copenhagen between the town hall square and Gammeltorv. It has been a common perception that the rampart and the moat made up the fortification around the oldest town formation. This is completely wrong. On the contrary, the size almost precisely corresponds to the size of the trelleborg fortress in Trelleborg in Scania. The fortification in Copenhagen thus must be remnants of a fortress. It has been built before any culture stratum could be formed. The missing traces of tiles in the culture strata around the fortress show that the time is around the middle of the 12th century. The only fortress types, which are known from this early period, are Harald Bluetooth´s trelleborg fortresses. Just outside the eastern rampart area remnants of the wooden church, St. Clemens, the oldest church in Copenhagen.
Trelleborg in Copenhagen? | 
The Circle of the Trelleborg today. |
Lund
Uppåkra outside Lund seems to have disappeared in the end of the 10th century and replaced by Lund just north of it. We may presume that it is the Christian Harald Bluetooth, who has shut down this pagan shrine and thus moved the power centre. That the newly built Lund should have been without fortifications seems quite improbable, when we know that there are at least two other fortifications in the Scania, which king Harald had just conquered. Today there is still a semicircle shaped street just north of the cathedral. The diameter corresponds to the size of the trelleborg fortress in Borgeby. Next to the fortress, which probably was situated in Lund is the wooden St. Clemens´ Church. That was the only of the many medieval Lund churches, which was owned by the king. In the area two of the oldest finds was made, bot from the end of the 10th century.
Trelleborg in Lund? |
Helsingborg
Helsingborg is referred to as a town as early as the year 1085. The name shows that there must have been a fortress (borg = fortress) there before then. The only fortress types known that far back, are king Harald´s trelleborg fortresses. The medieval tower ”Kærnan” was surrounded by a circular wall around the area, which in size corresponds to the well-known trelleborg fortresses. In maps there are just north of this area signs of ramparts, which may indicate the position of an earlier fortress. In the middle of the ramparts is the wooden St. Clemens´ church, the oldest church in Helsingborg. Excavated graves indicate that the church was built in the end of the 10th century. The position in relation to the church as well as the age of the church, indicate that king Harald may have been the builder.
Trelleborg in Helsingborg? |
Laholm
In the southern part of Halland is the town, Laholm by the river, Lagan. Laholm is the oldest town in Halland and the church has been consecrated for St. Clemens. Sea farers could not sail further up the river as waterfalls/gushing rivers render further sail impossible. North of the church there are still signs in the medieval street network that a round trelleborg fortress was situated here. Just north of the river there is a ” købing place”, i.e. a large trading place from the Viking Age. The topographical resemblance to Borgeby is very striking. Lagan leads into one of the richest areas in Småland. Here are many rune stones of the Danish kind. One of them says: ” Tumme erected this stone for Assur, his brother, who served king Harald as a sea warrior.”
Trelleborg in Halland |
Oslo
One the great rune stone in Jelling it says that king Harald conquered Norway. The preserved written material shows that the king especially was interested in the Oslo inlet. In the medieval part of town in Oslo there was a St. Clemens´ church. It was built in stone around the year 1100, but before that two wooden churches were there. The graves by the oldest wooden church have been dated to the period 980 – 1030. Just west of the church was the royal estate. The oldest construction has been some sort of fortification and in a smaller area archaeologists have been able to show that it was a slightly curved rampart. In front of the rampart there were large open ditches. In the light of the early dating of this fortification it is probable that this may have been a trelleborg fortress. In the 13th century the area is mentioned several times as ”the trælle mountain ”. |