Extending 135 km around the city of Amsterdam, this defence line (built between 1883 and 1920) is the only example of a fortification based on the principle of controlling the waters. Since the 16th century, the people of the Netherlands have used their expert knowledge of hydraulic engineering for defence purposes. The centre of the country was protected by a network of 45 armed forts, acting in concert with temporary flooding from polders and an intricate system of canals and locks.
The Stelling van Amsterdam is an excellent illustration of how The Netherlands defended itself against attack, ie by means of water. Water control and defence have gone hand in hand in the country since the 17th century. From time immemorial dikes, sluices, and canals have been built to drain the land; temporary flooding of the land forms the basis of the defensive system. This principle was first applied in the 16th century, during the struggle for independence from Spain, with the development of the Oude Hollandse Waterlinie.
The introduction of the new defensive system laid down in the 1874 vestingwet (law on the use of fortresses) meant that a number of old fortified towns, mostly in the east and south of The Netherlands, were relieved of their defensive role and so could expand outside their ramparts, which largely dated from the 17th century.
Under the terms of the Vestingwet, The Netherlands would be defended by nine defensive systems, most of which were already in existence. The new element was the defensive line around the nation's capital, Amsterdam, which would become the last redoubt. it had a predecessor in the form of earth batteries and semipermanent entrenchments to defend Amsterdam. This defensive line (the Nieuwe Hollandse Waterlinie) was almost complete in the mid-19th century, but it was partly superseded by the stelling van Amsterdam. The new system was so extensive that the entire infrastructure of the country was affected.
Work began on the Stelling in 1883 after lengthy discussions on its military and financial implications. Because it was based on flooding, use was made of the intricate polder system of the western part of The Netherlands. The decision was taken to build the forts along the main defence line in unreinforced concrete, a very early application of this material (first used at Newhaven in the United Kingdom in the 1860s).
In 1892 the northern end of the Nieuwe Hollandse Waterlinie was transferred to the Stelling, to form the eastern part of the defensive system. Certain modifications were carried out to the forts, in line with current military thinking. In the first phase forts were built at the mouths of the main watercourses leading into Amsterdam: a coastal fort at the mouth of the Noordzeekanaal, near Umuiden and an island fort and two coastal batteries in the u east of the city where it joined the former Zuiderzee.
The standard forts on the Stelling were built in two stages. Between 1897 and 1906 eighteen forts were built, and ten more, built to a modified design, were added between 1908 and 1914. The entire Stelling was manned throughout world war I, even though The Netherlands was neutral in that conflict. During this period construction work continued, to be completed in 1920.
Two years later the Netherlands Government revised its defensive plan and decided to build the Holland vesting, which included Part of the Stelling, which had become obsolete with the introduction of the aeroplane into warfare. Part of the flooding was activated when the German army invaded The Netherlands in May 1940, but no fighting took place. The early forts were not abandoned as defensive works until some time after the end of world War 11; some structures are still in use by the Ministry of Defence.