Near the German border, in Westerwolde (Southeast Groningen), is the fortress Bourtange.
In 1580 William of Orange gave the order to build a fort on the sand ridge in the Bourtanger moor, on the border of modern Germany. On the order of William Louis of Nassau the fortress was raised in 1593.
Between 1593 and 1851 Bourtange was an important fortress. An agrarian village came into being when the fortress was dismantled in 1851. Only a few buildings still remembered the glory of yesteryear. In the nineteen sixties the county of Vlagtwedde took the initiative to reconstruct the fortress. The plan was implemented between 1967 and 1992. Ramparts were again raised, ditches were dug and soldiers’ barracks were built.
References:Carlsten is a stone fortress built on the orders of King Carl X of Sweden following the Treaty of Roskilde, 1658 to protect the newly acquired province of Bohuslän from hostile attacks. The site of Marstrand was chosen because of its location and its access to an ice free port. Initially a square stone tower was constructed, but by 1680 it was reconstructed and replaced by a round shaped tower. Successive additions to the fortress were carried out, by the inmates sentenced to hard labour, until 1860 when it was reported finished. The fortress was decommissioned as a permanent defense installation in 1882, but remained in military use until the early 1990s.
The fortress was attacked and sieged twice falling into enemy hands. In 1677 it was conquered by Ulrik Frederick Gyldenløve, the Danish military commander in Norway and in 1719 by the Norwegian Vice-Admiral Tordenskjold. At both occasions the fortress was returned to Swedish control through negotiations and treaties.