Dutch Water Defence Lines, Netherlands

Water as an ally

Fortress island Pampus (1996) by Dutch Water Defence LinesUNESCO World Heritage

The Dutch Water Defence Lines were constructed to defend the economic heart of the Netherlands against military attacks. This UNESCO World Heritage site consists of the Defence Line of Amsterdam and the New Dutch Waterline. The fortress island Pampus, pictured, is part of both defence lines.

Naarden Vesting (1996) by Dutch Water Defence LinesUNESCO World Heritage


The idea behind the Dutch Water Defence Lines is to defend the Netherlands by intentionally flooding land. This principle, known as inundation, is very old. 

Structure along Korte Uitweg, Schalkwijk area near Utrecht (1996) by Dutch Water Defence LinesUNESCO World Heritage

Fundamental to the functioning of the Dutch Water Defence Lines was the modification of the land on which the system was constructed. Inundation basins, bounded by quays and dikes, were created in front of the defence line. 

A clear example of this strategically-modified landscape can be seen in the area of Schalkwijk, near Utrecht.

Inundation sluice in the Beemster (1996) by Dutch Water Defence LinesUNESCO World Heritage

The key aspect of this water management system was inundation: the controlled flooding of land using locks, dikes, canals, rivers and pumping stations. The water was 40 to 50 centimetres deep: too deep to wade and too shallow to sail. 

Fort near Krommeniedijk (1996) by Dutch Water Defence LinesUNESCO World Heritage

In some places, at the so-called accesses, where, for example, rivers, canals, dikes, roads or railways crossed the defence lines, inundation was not possible. Forts and other military structures were built here to protect the passageways. The army operated from the forts.

Secret of Man and Horse By Willy Kruijssen and Christel van Vliet at Polder Blokhoven near Schalkwijk (1996) by Dutch Water Defence LinesUNESCO World Heritage

In the early days, there was little control over the depth and extent of the inundations. With the construction of the New Dutch Waterline, inundations were much more manageable. Nowadays, some of the inundation fields are used as water storage areas for flooding during heavy rainfall. One such example is Polder Blokhoven, near Schalkwijk. 

Fort Vechten near Utrecht (1996) by Dutch Water Defence LinesUNESCO World Heritage

The New Dutch Waterline is the oldest of the two waterlines. There was a predecessor to the New Dutch Waterline, going back as far as 1672, which did not protect the city of Utrecht. In 1815 the order was given to include Utrecht in the waterline. As the area east of Utrecht was difficult to defend, extra forts were built.

Fort Pannerden (1996) by Dutch Water Defence LinesUNESCO World Heritage

The New Dutch Waterline is 85 km long, 3 to 5 km wide and extends between Muiden and the Biesbosch. Fort Pannerden, near the Dutch-German border, is the easternmost fortress, strategically located at the junction of the rivers Rhine and Waal and the Pannerdensch Canal.

Fort Everdingen (1996) by Dutch Water Defence LinesUNESCO World Heritage

During the construction of the New Dutch Waterline, much attention was paid to the vegetation on and around the forts. The plants had four different functions: to limit shell impacts through extensive root systems, to create a barbed wire effect, to act as camouflage, and to create pallisades and other defences.

Fort Abcoude (1996) by Dutch Water Defence LinesUNESCO World Heritage

The Defence Line of Amsterdam is 135 km long, consists of 46 forts and was built between 1880 and 1914. Before that, between 1805 and 1810, the colonel and engineer Cornelis Krayenhoff prepared inundations and access posts around Amsterdam, establishing a clear predecessor to the Defence Line.

Gun turret at Fort Spijkerboor (1996) by Dutch Water Defence LinesUNESCO World Heritage

The drainage of polders around Amsterdam and the newly-excavated North Sea Canal in the 19th century gave enemy armies a clear passage through to the capital. 

At the same time, around 1870, tensions in Europe were running high and major advances were being made in gun technology. The Netherlands was forced to radically revise its national defence.

Fort at Nekkerweg (1996) by Dutch Water Defence LinesUNESCO World Heritage

It was determined that a new circular defence line would be constructed around Amsterdam, which was to serve as the National Reduit: this was the Defence Line of Amsterdam. In the event of an enemy breakthrough, the army and government could withdraw to the reduit and await help from a friendly power.

Fort north of Purmerend (1996) by Dutch Water Defence LinesUNESCO World Heritage

At the time the Defence Line of Amsterdam was being constructed, it became clear that masonry forts were no longer strong enough to withstand modern heavy artillery and concrete was chosen as the preferred material. 

Fortress island near IJmuiden (1996) by Dutch Water Defence LinesUNESCO World Heritage

The forts of the Defence Line of Amsterdam were built according to a standard model which was modified over three different periods, as improvements were made to the design. 

There are some exceptions to this standard model that take local circumstances into account, such as the fort islands near IJmuiden and Pampus.

Cyclist in front of a group shelter (1996) by Dutch Water Defence LinesUNESCO World Heritage

During the First World War, the Dutch Water Defence Lines were mobilized to guarantee the neutrality of the Netherlands. In 1922, the New Dutch Waterline and the Defence Line of Amsterdam were merged under the name Vesting Holland. Concrete casemates and group shelters were added to aid the active defence of the waterlines.

Fort near Aalsmeer (1996) by Dutch Water Defence LinesUNESCO World Heritage

On the eve of the Second World War, parts of the water lines were inundated. After the surrender of the Netherlands, the German occupiers used the Vesting Holland in their defence against the Allies. 

Fort Hinderdam (1996) by Dutch Water Defence LinesUNESCO World Heritage

After the Second World War, the forts fell into disrepair. This allowed nature to take over in the more isolated spots, and special nature reserves were formed. Legislation which stipulated that building was not allowed around the forts kept the landscape open and green. Here, man has made a covenant with water and nature.

Fort de Batterijen (1996) by Dutch Water Defence LinesUNESCO World Heritage

Nowadays, there is a lot to experience at many of the forts of the Dutch Water Defence Lines. From restaurants and museums to unique places to stay, the site is full of secrets, stories and special objects. It is unique in the world and deserves to continue to exist for future generations.

Muiderslot (1996) by Dutch Water Defence LinesUNESCO World Heritage

The Defence Line of Amsterdam was inscribed on the UNESCO World Heritage List in 1996. To complete the story of the strategic use of water in the Netherlands, the New Dutch Waterline was added to the World Heritage site in 2021. 

The two defence lines together are a linear monument with a total length of 220 kilometres. 

Credits: Story

This exhibit was created by the Dutch Water Defence Lines site holder:
www.hollandsewaterlinies.com

More on the Dutch Water Defence Lines and World Heritage:
https://whc.unesco.org/en/list/759


Photos: Aerophoto Schiphol; Mike Bink; Jasha Dekker; Jessica de Korte; Abe Jonker; Luuk Kramer; Desiree Meulemans; Ossip van Duivenbode; Martin van Lokven; Kenneth Stamp; Wiebe de Jager.



Credits: All media
The story featured may in some cases have been created by an independent third party and may not always represent the views of the institutions, listed below, who have supplied the content.
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