Archaeologists in Poland found evidence of a 15th-century windmill ringed by defensive trenches

Beneath Windmill Hill, about 300 meters west of the medieval town of Puck in northern Poland, University of Warsaw archaeologists have mapped two circular trenches, one roughly 30 meters across and the other roughly 50, around what they believe was a 15th-century windmill. About a dozen stone cannonballs turned up nearby.

Dr. Michał Starski, who led the work for the university’s Faculty of Archaeology, calls the fortification reading a hypothesis. The finds fit it well enough that he has already named what they might represent: defensive moats, and by extension the first field fortifications of the Thirteen Years’ War.

Two ditches around a presumed windmill

The 2026 dig covered more than 5,000 square meters and recorded more than 300 archaeological features, according to HeritageDaily’s account of the excavation. The ditches stand out among them: each is about 1.5 meters deep and 1.5 to 2.5 meters wide, and the two rings sit one inside the other.

Inside the rings, the team found fragments of millstones that show late medieval manufacturing techniques, which is the main evidence tying the site to a mill rather than to some other structure. The ditches are also what separates the find from an ordinary mill site, since a hilltop mill needs no moat. A wooden cellar belonging to a neighboring building and the basement remains of a second, unidentified building complete the picture inside the enclosure. Medievalists.net reports the ditches may be defensive moats around the windmill, and that the interpretation remains preliminary.

Stone cannonballs and a war with sieges

The cannonballs are what push the idea from agricultural to military: the sources count about a dozen stone ones, and HeritageDaily and Medievalists.net agree on that scale, though Medievalists.net words it as more than a dozen. A windmill on a hilltop is not unusual; a windmill surrounded by two defensive ditches with stone shot in the ground nearby is.

The team places the likely setting in the Thirteen Years’ War, the 1454-1466 conflict between the Prussian Confederation, allied with the Kingdom of Poland, and the Teutonic Order. Puck saw two sieges in that war: Teutonic forces captured the town in 1460, and were themselves besieged there in 1464. Starski put the cautious version in his own words: “If these hypotheses are confirmed, then the first field fortifications from the Thirteen Years’ War have most likely been discovered.” In a separate remark on the season’s results, he said the verification of the team’s hypotheses “exceeded expectations,” with over 300 structures of various sizes discovered.

The war ended with the Second Peace of Thorn in 1466, which returned Pomerelia to Poland, made the Teutonic Order a Polish fief and created Royal Prussia under the Polish crown, with the war itself running from Feb. 4, 1454 to the autumn of 1466. Reference accounts of the war describe Puck as having a minor strategic role in the wider campaign and note that Polish and Prussian forces used early cannon, including bombards. Puck itself, per Wikipedia, was garrisoned by mercenaries hired by the Swedish king Charles VIII before the Teutonic Order took it in 1460.

A Lutheran cemetery on the same ground

The hill was used again after the fighting, and the burials are the best-documented layer reported from this season. Around 150 graves from a 16th-century Lutheran cemetery were found, with four coins dating from the 15th and 16th centuries and a clay tobacco pipe from the 17th century. Earlier occupation, from Lusatian-culture settlements in the first millennium BC to early medieval pits, shows the area was in use across more than two millennia.

The reported finds sit on a hill that shows continuous use for more than two thousand years, so the 15th-century ring of ditches and the later graves share ground with much older settlement traces. The sources describe the windmill-and-ditch reading as a working interpretation that rests on millstone fragments, the ditch dimensions and the stone shot, and the cemetery and the earlier occupation are the better-established layers on the site.

Starski’s earlier work in Puck

Starski is no newcomer to the town. A summary of his 2014-2015 excavation at 1 Maja Street, about 50 meters from the market square, describes a National Science Centre project on the material culture of late medieval Puck that yielded over 30,000 moveable finds and the remains of five residential buildings. Puck was already a marketplace and seaport by the 7th century, and a castle went up there in the late 14th or early 15th century. The town itself, per Wikipedia, received town status in 1348 and was returned to the Kingdom of Poland by Casimir IV Jagiellon in 1454, the year the war began.

Which of the two sieges, 1460 or 1464, the ditches belong to is a question the sources leave open, and Starski’s own wording, that the first field fortifications of the war have only “most likely” been found, keeps it open.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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