Amsterdam Defence Line

map of the inundation areas of the amsterdam defence line

During the Eighty Years’ War, the Watergeuzen flooded large areas. This was the simplest defense against the enemy. The flooded area was too deep to walk through, but too shallow to sail over.
The idea of ​​inundating land as a means of defense was redeveloped in the late 1800s by the War Department. The main purpose was to be able to protect Amsterdam during a war. Between 1880 and 1920 an enormous defensive circle was built around our capital: the Defence Line of Amsterdam.
This was located 15 to 20 kilometers around the center of Amsterdam. The Defense Line is 135 kilometers long and contains 45 fortresses. This would stop the enemy and Amsterdam would function as the last bastion of the Netherlands.
In the event of a hostile siege, sufficient food, water, fuel and military equipment had to be available within the position to last for six months.
Parts of the Haarlemmermeer and Beemster were placed within the defense to meet the need for pasture and agricultural land.
Coal depots and warehouses for food and grain were built.
The Nieuwe Meer became a storage facility for drinking water. Between 1901 and 1905, installations were set up here to pump and purify the water.
Artillery positions and gunpowder factories were built along the North Sea Canal.
The Defence Line consisted of two strategies, the inundations and the fortification.
The Defence Line of Amsterdam was never actively used, but it did have a deterrent effect. During the start of the First World War in 1914, it was a factor for the Germans not to invade the Netherlands.
The military significance lost the position after the First World War due to the development of the airplane. After that, however, it remained largely in use and its military status was not lifted until 1963. After that they were still used as storage warehouses and later on they became museums and art centers.
The first fortresses were made of brick, but the arrival of high-explosive shells made it necessary to use concrete instead of masonry.
The Defence Line is listed as a UNESCO World Heritage site since 1996.

https://www.stellingvanamsterdam.nl/en