Researchers have unveiled new findings about the artillery carried by Gribshunden, the Danish-Norwegian royal flagship that sank mysteriously off the Swedish coast in 1495. This late medieval vessel, now recognised as the best-preserved warship of its kind, offers an unparalleled look at the technological crossroads between the Middle Ages and the Age of Exploration.
The findings come from a new study published in the International Journal of Nautical Archaeology. The research team — Brendan Foley and Martin Hansson of Lund University, and Kay Douglas Smith, an independent English historian specialising in medieval artillery — combine archaeological, historical, and technical expertise to present the most comprehensive analysis yet of the ship’s weapons and their place in naval history.
A Royal Flagship and Floating Castle
Oak beds of artillery pieces recovered from the wreck of Gribshunden, curated at Blekinge Museum. Photo by Brendan Foley
Gribshunden was built in the Low Countries around 1484, from timber harvested in the Ardennes. By 1485 it was in the service of King Hans of Denmark and Norway. Unlike the Iberian monarchs who sponsored overseas voyages, Hans used his flagship closer to home. He personally sailed on it across the Baltic, employing it as a “floating castle” — a mobile royal stronghold to project power, travel to Norway and Gotland, and enforce authority throughout his realm.
The cost of such a vessel was staggering. Estimates suggest that the construction and equipping of Gribshunden may have absorbed up to 8% of Denmark’s national budget in 1485. For Hans, the ship was not only a display of military strength but also a political tool: a seaborne counterpart to a fortress. Its functions went beyond warfare, extending into diplomacy, administration, and even cultural representation.
Sinking at Ronneby
In June 1495, Hans was en route to a political summit in Sweden, where he hoped to unify the Nordic kingdoms under a revived Kalmar Union. While anchored off Ronneby, disaster struck. Contemporary sources describe an explosion and fire that destroyed the vessel while the king was ashore.
For centuries, the fate of Gribshunden was a mystery. Rediscovered by divers in the 1970s and identified in the early 2000s, the wreck rests in the Baltic Sea at a depth of less than 10 metres. The low salinity and cold waters of the Baltic preserved parts of the wooden structure and, most importantly, the oak gun beds that once supported the ship’s artillery. These remains are extraordinarily rare, as wrought-iron guns typically disintegrate in marine environments.
The Arsenal of Gribshunden
Phillip Short and Brendan Foley recover a gun bed from the wreck of Gribshunden, 2021. Image: Klas Malmberg.
Historical records suggest Gribshunden may have carried between 50 and 68 small-calibre guns, known as serpentines. These wrought-iron swivel guns, mounted on wooden beds, were primarily anti-personnel weapons. They were designed not to sink enemy ships but to incapacitate their crews, clearing the way for boarding and capture.
Archaeological investigation has so far recovered 11–14 gun beds from the wreck. Although the iron barrels have long since corroded away, their shapes were preserved in the beds, allowing researchers to digitally reconstruct the weapons. Using 3D modelling and printing, the team recreated the guns in detail, revealing how they were mounted and fired.
The artillery was sophisticated for its time. The guns were breech-loaded with interchangeable powder chambers, enabling rapid fire. Shot included lead balls with iron cores, several of which were found flattened, possibly due to the explosion that destroyed the ship.
A Rare Archaeological Bridge
Gun bed 29812.45 on the wreck site immediately after discovery in 2022, and rendering from 3D model. Images: Brett Seymour, 2022; Carolina Larsson, Lund University HumLab.
The significance of Gribshunden lies in its timing. Built a few years before Columbus crossed the Atlantic and Vasco da Gama rounded the Cape of Good Hope, it represents the exact type of ship-and-gun combination that allowed Europeans to dominate the seas.
Whereas Iberian powers used similar vessels for exploration and colonisation, Hans employed Gribshunden to consolidate his Baltic empire. The ship thus provides a unique Nordic comparison to Iberian “ships of discovery.”
Researchers note that this was a transitional moment in naval warfare. Gribshunden was built with a carvel hull, a design that allowed for larger ships and heavier armament. Yet it shows no evidence of gunports for mounting heavy cannon — a technology that would soon revolutionise naval combat. Instead, its weaponry reflects the late medieval emphasis on swivel guns for close-range engagements.
Excavation and Reconstruction
Only a small portion of the wreck has been excavated so far, yet findings are already remarkable. The keel, sternpost, and sections of the superstructure survive, alongside the ship’s enormous rudder and even its dramatic figurehead — a fantastical beast devouring a screaming man, now conserved and displayed at the Blekinge Museum.
Digital archaeology has been key to reconstructing the lost artillery. The team used photogrammetry and structured light scanning to capture the gun beds, producing scale models that recreate how the weapons functioned.
The work has revealed three distinct types of guns aboard Gribshunden:
Long stave-built wrought-iron tubes.
A shorter gun with a larger bore, possibly for firing stone shot.
A unique wrought-iron tube with no reinforcing bands, unlike its counterparts.
This variety suggests experimentation in shipboard artillery during the late 15th century, as gunsmiths and shipwrights adapted to the new challenges of naval warfare.
Preserving the Legacy
Today, the Gribshunden artifacts are curated by the Blekinge Museum, with select items displayed in Ronneby and Helsingør. Plans are underway for a dedicated museum in Ronneby that will permanently house the ship’s remains and its weaponry.
For Brendan Foley, the project has been both thrilling and intellectually rewarding. “Diving on this late medieval royal shipwreck is of course exciting,” he says. “However, the greatest satisfaction is when we can actually put the pieces of the puzzle together later on; combining Martin’s castle expertise with Kay’s deep understanding of artillery.”
The article, “Late Medieval Shipboard Artillery on a Northern European Carvel: Gribshunden (1495),” by Brendan Foley, Kay Douglas Smith and Martin Hansson, is published in the International Journal of Nautical Archaeology. Click here to read it.
Viking Ship Museum archaeologist Marie Jonsson holds a crossbow stock recovered from Gribshunden in 2021. Photo by Staffan von Arbin
We have reported on finds from the Gribshunden before. See:
Top Image: Gun bed GH2021-A100 discovered in 2021, with gun bed 29704:237 positioned behind. Powder chamber 29704:7 lies under the measuring tape. Photo by Klas Malmberg
Researchers have unveiled new findings about the artillery carried by Gribshunden, the Danish-Norwegian royal flagship that sank mysteriously off the Swedish coast in 1495. This late medieval vessel, now recognised as the best-preserved warship of its kind, offers an unparalleled look at the technological crossroads between the Middle Ages and the Age of Exploration.
The findings come from a new study published in the International Journal of Nautical Archaeology. The research team — Brendan Foley and Martin Hansson of Lund University, and Kay Douglas Smith, an independent English historian specialising in medieval artillery — combine archaeological, historical, and technical expertise to present the most comprehensive analysis yet of the ship’s weapons and their place in naval history.
A Royal Flagship and Floating Castle
Gribshunden was built in the Low Countries around 1484, from timber harvested in the Ardennes. By 1485 it was in the service of King Hans of Denmark and Norway. Unlike the Iberian monarchs who sponsored overseas voyages, Hans used his flagship closer to home. He personally sailed on it across the Baltic, employing it as a “floating castle” — a mobile royal stronghold to project power, travel to Norway and Gotland, and enforce authority throughout his realm.
The cost of such a vessel was staggering. Estimates suggest that the construction and equipping of Gribshunden may have absorbed up to 8% of Denmark’s national budget in 1485. For Hans, the ship was not only a display of military strength but also a political tool: a seaborne counterpart to a fortress. Its functions went beyond warfare, extending into diplomacy, administration, and even cultural representation.
Sinking at Ronneby
In June 1495, Hans was en route to a political summit in Sweden, where he hoped to unify the Nordic kingdoms under a revived Kalmar Union. While anchored off Ronneby, disaster struck. Contemporary sources describe an explosion and fire that destroyed the vessel while the king was ashore.
For centuries, the fate of Gribshunden was a mystery. Rediscovered by divers in the 1970s and identified in the early 2000s, the wreck rests in the Baltic Sea at a depth of less than 10 metres. The low salinity and cold waters of the Baltic preserved parts of the wooden structure and, most importantly, the oak gun beds that once supported the ship’s artillery. These remains are extraordinarily rare, as wrought-iron guns typically disintegrate in marine environments.
The Arsenal of Gribshunden
Historical records suggest Gribshunden may have carried between 50 and 68 small-calibre guns, known as serpentines. These wrought-iron swivel guns, mounted on wooden beds, were primarily anti-personnel weapons. They were designed not to sink enemy ships but to incapacitate their crews, clearing the way for boarding and capture.
Archaeological investigation has so far recovered 11–14 gun beds from the wreck. Although the iron barrels have long since corroded away, their shapes were preserved in the beds, allowing researchers to digitally reconstruct the weapons. Using 3D modelling and printing, the team recreated the guns in detail, revealing how they were mounted and fired.
The artillery was sophisticated for its time. The guns were breech-loaded with interchangeable powder chambers, enabling rapid fire. Shot included lead balls with iron cores, several of which were found flattened, possibly due to the explosion that destroyed the ship.
A Rare Archaeological Bridge
The significance of Gribshunden lies in its timing. Built a few years before Columbus crossed the Atlantic and Vasco da Gama rounded the Cape of Good Hope, it represents the exact type of ship-and-gun combination that allowed Europeans to dominate the seas.
Whereas Iberian powers used similar vessels for exploration and colonisation, Hans employed Gribshunden to consolidate his Baltic empire. The ship thus provides a unique Nordic comparison to Iberian “ships of discovery.”
Researchers note that this was a transitional moment in naval warfare. Gribshunden was built with a carvel hull, a design that allowed for larger ships and heavier armament. Yet it shows no evidence of gunports for mounting heavy cannon — a technology that would soon revolutionise naval combat. Instead, its weaponry reflects the late medieval emphasis on swivel guns for close-range engagements.
Excavation and Reconstruction
Only a small portion of the wreck has been excavated so far, yet findings are already remarkable. The keel, sternpost, and sections of the superstructure survive, alongside the ship’s enormous rudder and even its dramatic figurehead — a fantastical beast devouring a screaming man, now conserved and displayed at the Blekinge Museum.
Digital archaeology has been key to reconstructing the lost artillery. The team used photogrammetry and structured light scanning to capture the gun beds, producing scale models that recreate how the weapons functioned.
The work has revealed three distinct types of guns aboard Gribshunden:
This variety suggests experimentation in shipboard artillery during the late 15th century, as gunsmiths and shipwrights adapted to the new challenges of naval warfare.
Preserving the Legacy
Today, the Gribshunden artifacts are curated by the Blekinge Museum, with select items displayed in Ronneby and Helsingør. Plans are underway for a dedicated museum in Ronneby that will permanently house the ship’s remains and its weaponry.
For Brendan Foley, the project has been both thrilling and intellectually rewarding. “Diving on this late medieval royal shipwreck is of course exciting,” he says. “However, the greatest satisfaction is when we can actually put the pieces of the puzzle together later on; combining Martin’s castle expertise with Kay’s deep understanding of artillery.”
The article, “Late Medieval Shipboard Artillery on a Northern European Carvel: Gribshunden (1495),” by Brendan Foley, Kay Douglas Smith and Martin Hansson, is published in the International Journal of Nautical Archaeology. Click here to read it.
We have reported on finds from the Gribshunden before. See:
Spectacular discoveries made during excavation of 15th century warship
Researchers present new finds from Gribshunden shipwreck
Sunken medieval warship continues to offer up its secrets
Top Image: Gun bed GH2021-A100 discovered in 2021, with gun bed 29704:237 positioned behind. Powder chamber 29704:7 lies under the measuring tape. Photo by Klas Malmberg
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