2,400-Year-Old War Vessel in Denmark Reveals Rare Fingerprint and New Origin Story
For more than a century, the Hjortspring boat has carried an enduring mystery. The 2,400-year-old war canoe – discovered on the Danish island of Als and intentionally sunk after an attack involving around 80 warriors – was in an extraordinary state of preservation, but a crucial question remained unanswered: where did it come from?
An analysis of the ship’s caulking and ropes produced the strongest clue yet. The study, published in PLOS Onediscovered that the waterproofing was composed of animal fat mixed with pine pitch – a chemical signature that points to pine-rich regions along the Baltic Sea rather than Denmark itself. Also discovered: a partial human footprint embedded in the caulking – which could offer an even more direct link to the warriors who once occupied the ship.
“The Hjortspring boat is the only prehistoric plank boat discovered in Scandinavia,” explains Mikael Fauvelle, associate professor and researcher at the Department of Archeology and Ancient History at Lund University. “Because the Hjortspring boat was deliberately sunk in a bog as an offering, it was preserved in a unique low-oxygen environment for over [2,000] years, making it the only preserved example of one of these boats that we own.
Clues in the caulking reveal a Baltic origin
Radiocarbon dating of materials associated with the ship gave a range of 381 to 161 BCE, placing its construction firmly in the pre-Roman Iron Age and aligning with previous estimates of the site.
Dated Bronze Age art, Early Iron Age art from Brastad and the Hjortspring boat comparison.
(Image credit: 3D model by Richard Potter; Fauvelle et al., 2025, PLOS One, CC-BY 4.0)
While the chemical signature of the caulk points strongly toward regions east of Denmark, the researchers note that pine pitch could theoretically have reached the region through trade. But if the boat itself set out from the Baltic coast, reaching Als would have required a long journey across open water – a journey that suggests careful planning, coordination and intention.
“This means that the boat’s crew traveled hundreds of kilometers by sea to launch their attack on Als, in southern Denmark,” explains Fauvelle. “Although we will never know exactly what caused around 80 warriors to attack Als around 2,400 years ago, these results suggest that it was an interregional conflict that involved significant planning and logistical capabilities.”
Fauvelle adds: “Such long-distance maritime raids are quite similar to what we see during the much later Viking period. […]. Our results suggest that this pattern of maritime trade and long-distance raiding may have characterized Scandinavian societies for thousands of years.
Left: Fingerprint caulking fragment; Right: High-resolution X-ray tomography scan of a fingerprint.
(Image credit: Photography by Erik Johansson, 3D model of Sahel Ganji; Fauvelle et al., 2025, PLOS One, CC-BY 4.0)
The team’s identification of a fingerprint in the caulking adds a rare human detail to this larger picture: a small but tangible connection to one of the people responsible for maintaining the ship during its lifespan.
Learn more: 3,000-year-old Uluburun shipwreck reveals ancient trade routes
A century-old mystery about to be solved
First excavated in the early 20th century, the Hjortspring ship has long intrigued researchers because the weapons and shields found with it were common throughout northern Europe, offering no clues to the origin of its crew. The team now hopes to extract ancient DNA from the caulk – including the fingerprint – which could offer an even more direct link to the people who once used the container.
Fauvelle says the results point to two broader perspectives. The first is that long-distance travel and conflict were already a part of life in the Early Iron Age, showing that ancient Scandinavian societies were socially and politically complex.
The second is the magnitude of advances in archaeological science: modern techniques now allow researchers to study the boat in ways that would have been impossible for the first excavators a century ago, opening the door to even more discoveries as these methods continue to develop.
Learn more: Ancient ship wreck sheds light on Iron Age trade and a lost Mediterranean port
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