Fort Pannerden was constructed between 1869 and 1871 to serve as part of the New Dutch Waterline. Originally built completely out of brick and mortar, with just one main battery guarding the Rhine, it was upgraded significantly during 1885-1895. The main battery was completely rebuilt, with armour and concrete, while two additional armoured batteries were added and the roof of the fort was reinforced with concrete. The fort had strategic significance in that it guarded the Pannerden Canal, which supplied the water for the inundations of the New Dutch Waterline and could potentially be used as a route towards the main line of defence, but the fort saw little active service.
In World War I the Netherlands remained neutral, although the fort was manned as part of a general mobilisation. In World War II on May 10, 1940, during the German invasion of the Netherlands, the fort was first bypassed and then surrounded. On May 11, cut off from the rest of the Dutch army, the commander of the fort surrendered under threat of artillery bombardment and air attack. Most of the fort was subsequently stripped of all useful materials and after 1945 the building fell into disuse.
References:Sigmaringen Castle was first mentioned in the year 1077 in the chronicles of Petershausen monastery. The oldest parts of the castle are concealed beneath the alterations made during the 17th and the 19th centuries. The secret of the earliest settlement built on this defendable rock will never be fully revealed: large-scale excavation work would be necessary, which the extensive land development renders impossible. Judging from the many Roman remains unearthed in the area around Sigmaringen, the 12th century keep known as the 'Roman Tower' could be traced back to a Roman predecessor.
The castle remains that have been preserved (gate, great hall and keep) date back to the Staufer period around 1200. The castle remains were integrated into subsequent buildings. The foundations of the castle buildings are to a large extent identical to the surrounding castle wall.
These remains give us a good idea of how the castle might have looked during the 12th century.