Defence Line of Amsterdam

Meeting modern demands

The idea for the Defence Line arose in the 19th century when tensions in Europe were running high. There was a war between Prussia, Denmark and Austria and between Germany and France. Given all the wars, and the increasing power of modern weaponry, the Dutch decided that the country’s defences needed an update.

The Fortification Act of 1874 ordered the construction of a new line of forts around Amsterdam: the Defence Line of Amsterdam. The first to be built was Fort Abcoude, but because it hadn’t been designed to withstand the latest artillery, it proved to be obsolete no sooner than it was completed. The construction of the subsequent fortresses was thus delayed so the design could be modernised. The interval lasted ten years. The final plan was completed in 1894.

Standard forts

The forts were built according to a standard model: they were around 4.60 metres high, with concrete walls 1.50 metres thick, surrounded by a moat with a bridge, and with a bombproof building inside including sleeping quarters, a kitchen, a canteen, washrooms, a hospital and a telegraph room. All the forts were completed by 1914, just in time for the First World War. The forts were kept ready for action throughout the war, but because the Netherlands remained neutral, an attack never came, and the soldiers manning the forts had little to do. The Defence Line proved to be unnecessary. However, although the line may not have seen action during the First World War, it did act as a deterrent and was a significant reason why the Germans didn’t invade the Netherlands.

The Second World War

With the increasing dominance of air warfare after the First World War, the Defence Line lost its military significance. At the start of the Second World War, the Northern Front and the Southeast Front of the Defence Line were indeed flooded, but the enemy simply flew overhead. When the Dutch army surrendered, the German occupiers soon took over the forts and other parts of the Defence Line.

Fort IJmuiden was particularly useful to the Germans. It became an important bulwark in the Atlantic Wall, the more than 5000-kilometre system of defences along the coast of continental Europe. The bunkers built by the German troops and the wall markings they left behind are tangible reminders of the occupation.

New uses

After the Second World War, the Defence Line finally became redundant. Some forts were used to imprison political offenders, such as members of the National Socialist Movement and collaborators, and later also Dutch soldiers who refused to fight in the military action to put down the Indonesian National Revolution against Dutch colonial rule – the murals at Fort Spijkerboor are a remnant of this era. The forts were also sometimes used to store munitions. When all the forts had lost their defensive status around 1960, the Ministry of Defence handed them over to the government property department to be sold to municipalities or, very exceptionally, to private individuals.

The Defence Line of Amsterdam Foundation was established in 1996 to bring the Defence Line’s cultural and historical significance to the attention of a wider public. In the same year, the Defence Line was listed as a UNESCO World Heritage Site. This acted as a boost, and from then on, more and more forts were opened to the public. All the forts have now been restored and repurposed. Fort on Nekkerweg is now the wellness centre of Fort Resort Beemster. Forteiland IJmuiden can be hired for meetings, courses and corporate events and is open to the public every first Sunday of the month between March and November and Kunstfort bij Vijfhuizen is a centre for contemporary art. On Fort Island Pampus, there is a visitors’ centre for the Defence Line of Amsterdam.

See all the forts here.