Where Jutland is at its narrowest the fortress consisted of several ramparts. It is about 40 km. from the North Sea in the west to Slien in the east, where Slesvig is today. It would have been almost impossible for the Vikings to build and defend a rampart of 40 km. Fortunately it wasn’t necessary since the western part of the country was blocked by rivers and meadows. Only in the east where the Jutland Army Road passes was there an avenue of attack for the enemy. This was a distance of about 8 km.
The oldest ramparts are ‘Hovedvolden’ (a) and Nordvolden (b). Dendrological studies show that the oldest wood in these ramparts are from 737. Ongendus was king at this time so it was perhaps he that was responsible for their construction.
The next rampart was built by King Godfred in 808. Most indications are that it was ‘Kovirke’ (d) which provides very good protection for Hedeby.
The last ramparts were ‘Krumvolden’ (e) and ‘Forbindelsesvolden’ (f) which are from 968 when Harald Bluetooth was king. Together with ‘Hovedvolden’ (a) and ‘Halvkredsvolden’ around Hedeby they create one continuous rampart.
The German Keiser attacked the rampart and even though Harald Bluetooth got help from Haakon Jarl of Trondelag in Norway he was forced to retreat. He later recaptured the rampart, surely with help from the knights (rinborgerne).
The rampart was later reinforced with huge boulders and during the reign of Valdemar the Great with bricks.