Remains of the shipping blockade from the Eighty Years’ War in the IJ of 1573 have been found. At the time, shipwrecks were used to block access to the IJ. After the 2023 campaign, which revealed no traces of the blockade, specialists decided to make one more search attempt. And with results.

The Rijksdienst voor het Cultureel Erfgoed (RCE), the City of Amsterdam and the Amsterdam company Periplus Archeomare are working together on this project.

All historical data and maps have been reviewed, with the main result being that the search area has been shifted several tens of metres to the east. A new field survey was then carried out on 11 November. Under the supervision of the Amsterdam archaeological research firm Periplus, drilling was carried out from a working vessel at predetermined, promising locations in the IJ soil. These were geological borings with a diameter of 6 -7 cm.

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Shipwreck with brick

The results of the drilling survey were compelling. At a depth of about one metre in the IJ soil, the researchers came across an oak object. This location was then investigated further with additional borings. This established that a wooden shipwreck measuring 5 metres wide and at least 10 metres long was located here.

Most convincing are the drill holes that revealed brick in addition to oak. At the centre of the wreck lies a package of bricks, mortar and natural stone about half a metre thick. This establishes a direct link with the remains of the church of Schellingwoude mentioned in written sources, which was used to sink the wrecks.

The conclusion is that the wreck, traced within the new search area, is most likely related to the IJ blockade of 1573. Additional dating research has yet to provide complete certainty.

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Shipping blockade

At the beginning of the Eighty Years’ War (1568-1648), Amsterdam was still allied with the Spanish and, for this reason, the Sea Beggars wanted to cut the city off from its main lifeline: the IJ and thus the Zuiderzee.

Chronicles show that to this end, shipwrecks and other obstacles were sunk between Schellingwoude and the Diemerdijk: the narrowest stretch of the IJ. The first blockade was unsuccessful, a number of ships drifted up and so much-needed grain ships were still able to reach Amsterdam.

It did not stop at this one attempt. In April 1573, the sinking of wrecks using fragments of the church of Schellingwoude and tombstones is again reported. Finally, in September of the same year, the Spanish Admiral Bossu still managed to sail through the blockade with the flagship the Inquisition and a fleet of about thirty ships. It was the prelude to the Battle of the Zuiderzee in October the same year. At this battle, Bossu’s ship would be captured by the Beggars and the admiral was captured.

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Special archaeological underwater monument

This find has charted a relatively unknown piece of Amsterdam’s history. No decision has yet been made for any follow-up steps. It is likely that besides this one wreck, more remnants of the ship blockade must be present in the IJ bottom. What is certain is that the wreck will remain at the site, giving the city a special underwater archaeological monument. Consideration will have to be given to how to make this more experienceable.

Picture: Excerpt from Bilhamer/Beeldsnijder’s map of 1575, made shortly after the blockade in the river IJ, the blockade is indicated in Dutch (picture by RCE).

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