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Operational sites and bases

Planned Tactical Battle Sites

Land Defense



Full name of site:

IJssellinie / IJssel Defense Line


Haereweg 4b, 8121 PJ Olst, Holland

Operational period:




Primary user:

Netherlands Army


The IJssel Line was established in the beginning of the 1950s, intended to delay an attack by the Warsaw Pact, thereby providing the time needed for additional military support, principally from the United States and Great Britain.

In order to create a 126 kilometer long water barrier along the IJssel (from Arnhem to Kampen) and a section of the Rhine River (from Lobith to Arnhem) an enormous amount of water was needed. By damming the Waal River near Nijmegen and the Lower Rhine River near Arnhem/Oosterbeek it was possible using the water flowing into the Netherlands at Lobith to inundate the entire IJssel Valley.

The key elements of the IJssel Line were three movable floating dams (90 meters long at Olst and Arnhem and 240 meters at Nijmegen) with which the normal flows through the IJssel River could be blocked off to create a long and narrow shallow inland sea in the IJssel River Valley.

The water reservoirs created by the dams could then be released inside the protective winter dikes by means of water intake works, large sluices that could be opened to set huge areas of land under
water, forming an obstacle five to ten kilometers wide. A system of bunkers and gun batteries served to defend the dams and the IJssel Line.

During the 1960s the NATO line of defense was relocated to the Weser River, thereby making the IJssel Line superfluous. During the second half of the 1960s, approximately half of the defence works in Olst/Welsum were dismantled.

The IJssel Line was built in the 1950s under the most secret circumstances possible. Few military officers or elected officials knew the details. The more than 400,000 valley residents, who would have had to evacuate if the IJssel Valley were flooded, knew nothing about the plans. Only in 1990 was the secrecy surrounding the IJssel Line removed.


Various owners, ranging from local authorities and waterboards to private owners.

Valuation of authenticity and integrity:

Baseline 1965. Most of the primary infrastructure has been dismantled and removed. Smaller elements remain such as working harbours from which the dams would be deployed, inlet sluices, bunkers and gun battery emplacements.

Status and access:

Access: Partial. Public access to parts of the exterior areas. A number of the remaining elements at Olst can be visited by the public. None of the sites at Nijmegen and Arnhem are open to the public.

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