The Dutch Water Line

On 1573 at the beginning of the eighty years war against Spain, the Dutch used for the first time water by flooding the land to break the siege of
Spanish troops on the town Alkmaar.

Because much of Holland is below sea level, this tactic could be used and was applied frequently throughout this war.
In 1574, flooding the land prevented Spanish troops seiging Gorinchem which town took the side of the Prince of Orange in 1572.

Have patience, to see great pictures !!                                                                                                  Last revised on 16-mrt-2014

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Also in 1574, Spanish troops besieged the town (upper right) Leiden.
Then the Dutch flooded the land around the town.

As you can see, the Spanish made strongholds with little dikes like walls around them, also controlling the river to the town.

However the water level on the flooded land became high enough to allow a fleet of Dutch freedom fighters, named "Geuzen", to row their boats around the Spanish strongholds and free the town.
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In 1629 Prince Frederik Henderik starts executing a plan from 1589 made by Prince Maurits, for a defense line, making use of a string of pieces of land, that can be flooded in front of the defenders.

The line runs at first from the inland sea "Zuiderzee" in south direction to the first big river and is later on extended to the river "Merwede" at Gorinchem.

Holland was the rich part and economical center of the Netherlands housing also the government.

The defense line was made in the most easterly part of Holland that could be flooded easily.

Further to the east there was higher ground, that could not be flooded very easily. Also this part of the land had mostly agricultural activity and was less important to defend.

This picture shows the first line and the invading forces at several occasions in time.


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The line was used successfully against the invasion of the French in 1672.

However with the second invasion of the French in 1794, the winter was very severe and the flooded land and big rivers were completely frozen.

So in 1795, despite Dutch troops on skates and sledges fitted with guns, the French were able to concur Holland.

This picture shows the French crossing the ice.

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When the line was flooded, the with dike like walls fortified towns are like fortified defense islands in the water.

They protect the dikes which were running along the towns.
Guns were placed on the town walls, covering the dikes.

The dikes were the only roads, rising above the water surface.
So the dikes were the only roads, the enemy could use.

As you can see, the line was later on extended to the south into a swamp area called "De Biesbos".

Now Holland was completely sealed off against invasions over land.

In that time invasions over sea were not usual and considered to be very difficult.

The Dutch also had a very strong fleet with fast ships and very able commanders that even took on the British fleet occasionally.


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On other parts were no fortified towns were near dikes, that were crossing the waterline, or pieces of high ground, small fortresses were built as shown on this picture.
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The Dutch used flat boats fitted with a cannon.
At night, they beamed or rowed the boat silently over the flooded land to  the enemy line at the other side.
Then they fired the gun and all of their muskets and vanished in the night or fog.
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This picture shows the town Naarden, which is today the finest example of fortified towns in the Netherlands.

The Dutch kept improving the line in between various invasions and treads.

They fortified all towns in the line and built more and bigger fortresses according to the latest strategic building views.

Also more sluice gates were made in the dikes, to improve flooding.

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Between 1816 and 1824, the line is shifted a bit to the east, to get the town Utrecht in the middle of the Netherlands,  behind the line also.

However this was a bit higher ground, so more sluice gates were built to improve flooding of this new piece of the line.
Also 11 new fortresses were built, at some distance around the east side of Utrecht.

Between 1840 and 1860, important fortresses were equipped with a round gun tower made with very thick brick walls and buildings covered with earth, protecting the soldiers against enemy guns.

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Fortresses were also enlarged and equipped with more thick brick and ground covered building.

The thick brick buildings and gun towers could withstand direct hits from enemy artillery.

However the development of artillery went ahead on the development of the fortresses.

When guns and grenades got powerful enough to destroy the thick brick gun towers, the upper layer was removed and the remaining part protected against direct hits, with a ring of ground covered buildings at the enemy side.

The gun towers were now used to accommodate the soldiers and as storage room.

When under attack, the guns and soldiers were now deployed in field gun positions along the fortress walls.

The fortress on this draft picture is "Fort Honswijk", which was also protecting the north side of the big river "De Lek".

Under, you see the gun tower with a protective ring of 180 degrees.
There are many other thick brick ground covered buildings, used to store field guns and ammunition.

Also there are many field gun positions visible along the walls of the fortress.


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The fortresses were built with the gun tower in the middle of the dike, the dike was then led around the fortress, running away from the center of the gun tower.

So the guns had plenty of opportunity to blaze the enemy off the dike, if they tried to get around the fortress.

The enemy had to use the dike because anything else was flooded with water.

The fortress on this aerial photograph is "Fort Everdingen", which was also protecting the south side of the big river "De Lek".

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Here you see an aerial view of Fort Vuren at 4 km east of Gorinchem.

Most of these big fortresses were not only protecting the dikes, but also the big rivers.

Fort Vuren protected the North side of the big river Waal, which changes name after passing Fort Vuren and is then called Merwede, at Gorinchem.

Opposite to Fort Vuren on the south side of the river "De Waal" is fortress Loevestein, a fortified medieval castle, protecting the south side of the river.

Fort Vuren started as an arrow-shape front protected position for field guns, in fortification terms this is called a "Lunet", see the point-shape in the left upper corner of the picture.
The gun tower that you see in the center left of the upper part of the picture was built later and also the Lunet got an extension to the north with a ground covered gun storage room, as you can see at the underside of the picture.

Fort Vuren is in the summer season open for visitors. A boat tour starting in Gorinchem can be made, visiting the small fortress town Woudrichem, the fortified castle Loevestein and Fort Vuren. Hikers can also spend the night at Fort Vuren. Some other fortresses are also open for visitors.

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Soldiers of the garrison of Gorinchem are exercising with their modified "fortress guns" on the town walls of Gorinchem in the year 1935.

To be exact, the guns are positioned on the south-east side of Bastion 9.

They are pointing to broadside-forward on the Merwede dike and river.


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The fortresses and surrounding landscape were carefully designed, to blend the fortresses and other gun positions into the landscape.

This was done by presenting low and vague contours for the defense works when looking from east and south directions.

They used ground covering and also bushes and trees of the same kind as in the surrounding landscape.

Existing tree lines were extended to cover fortresses.

However the fortresses did have far less trees and bushes as they have now and also firing lines were kept open.

This is a view of the approach from the east at 500 m from Fort Honswijk.
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This is a view of the approach from the east at 500 m from a fortified gun position.

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This is a view from the east on a defense line  between fortresses.
The line is equipped with gun positions and shelters.
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With the invention of the high explosive shell the thick brick gun towers and shelters became obsolete.

During an attack the troops and guns were now more spread out over the terrain of the fortresses in small shelters and gun positions connected by trenches.

Later on, small concrete shelters were built.
This picture shows such a shelter (on the left) on Fort Vuren.

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On the picture on the left you see the flooding gate at Fort Asperen (8 km north/ east) of Gorinchem in action in the year 1939.
The Dutch waterline was prepared against the German treat.
The picture on the right shows the result.
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The landscape of Holland is covered with a maze of ditches and small canals.
When the land is flooded, these become invisible as well as the roads.
This forms a treacherous obstacle for enemy troops.

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In strong winters, the defensive value of the Dutch Water Line was decreased, when the ice on the big rivers and flooded land became thick enough for man and light vehicles to cross.
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However, the ice was cut open using special tools like the sawing truck shown on the left picture.
Ice shelves were put upright to form obstacles.
Also a bit of water was let off the flooded land, which created weak spots in the ice.
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Most of the Dutch were good skaters, what allowed the troops to move fast when the flooded land was frozen over.

They did know the locations of the weak spots in the ice, they did create.
However, the enemy did not.

This picture was taken during the mobilization of the troops to  positions in the Dutch Water Line in 1939/1940.


World War 2 started and on the 10 th of May 1940, the Germans opened the attack on Holland with a lot of airplanes. They were hunter, bomber , troop-transport and flying boat type airplanes.
Also for the first time in a war, extensive use of paratroopers was made
, by dropping them around the government center behind the Dutch Water Line in an attempt to capture airfields, government and queen to enforce a quick surrender.

Also paratroopers were dropped, to secure bridge heads at traffic and railway bridges over the big rivers at the south-west of Holland. A pantzer army was cruising blitzkrieg style through the south of the Netherlands, towards the bridge heads.

This was all behind the The Dutch Water Line.
It was then clear, that air power and fast mechanized army's had reduced the importance of the Dutch Water Line very much.


This page was updated on 16-03-14

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