Underwater 'yellow-brick road' leads divers to long-lost slave ships that sunk in the 18th century

Daily Mail​

05-05-2025

Marine archaeologists have found a 'yellow-brick road' at the bottom of the Atlantic Ocean that led them to the discovery of two long-lost Danish slave ships.
According to historical records, the ships, called Fridericus Quartus and Christianus Quintus, wrecked off the coast of Central America in 1710.
Fridericus Quartus was set on fire, while Christianus Quintus had its anchor rope cut and was destroyed in the surf. But for three centuries, no one knew exactly where the remains of these ships were.
In Costa Rica, people had long been aware of two shipwrecks located off the coast of Cahuita National Park, but dismissed them as sunken pirate ships.
That changed in 2015, when American marine archaeologists found yellow bricks from one of the wrecks, which raised new questions about their history.
Researchers from the National Museum Of Denmark and the Viking Ship Museum conducted an underwater excavation of the ships in 2023, taking samples of wood from one of the wrecks, the bricks, and recovering several clay pipes.
The team published their analysis of the objects on Sunday, revealing that the shipwrecks are, in fact, the missing remains of Fridericus Quartus and Christianus.
Co-researcher David Gregory of the National Museum Of Denmark said: 'The analyses are very convincing and we no longer have any doubts that these are the wrecks of the two Danish slave ships.
'The bricks are Danish and the same goes for the timbers, which are additionally charred and sooty from a fire. This fits perfectly with the historical accounts stating that one of the ships burnt.'
Measurements of the bricks revealed that they were the same size as the 'Flensburg' yellow bricks that were used in Denmark and the Danish colonies during the 1700s.
Analysis of their clay confirmed that it came from Denmark - either from a beach called Iller Strand or a small town called Egernsund.
Both places are located near the Flensburg Fjord, which was home to a large brick-producing industry in the 18th century, according to the National Museum Of Denmark.
The researchers used tree-ring dating to determine where oak wood extracted from one of the wrecks came from, finding that it originates from a tree in the western part of the Baltic Sea that was cut down sometime between 1690 and 1695.
The wood was also charred and sooty, which aligns with historical reports about one of the ships being set ablaze.
The clay pipes offer further evidence that the ships were Danish, as they proved to be Dutch-produced pipes that were commonly found onboard Danish ships at the time.
'The size, shape and patterns of the pipes suggest that they were produced in the period right before the ships became wrecked in 1710,' according to the researchers.
Gregory led the study alongside marine archaeologist Andreas Kallmeyer Bloch, who has been working for years to determine the origins of the Costa Rica shipwrecks.
Bloch said: 'It's been a long process and I've come close to giving up along the way.
'But this is undoubtedly the craziest archaeological excavation I've yet been part of. Not only because it matters greatly to the local population, but also because it's one of the most dramatic shipwrecks in the history of Denmark, and now we know exactly where it happened.
'This provides two pieces that have been missing from the history of Denmark.'
Denmark banned the transatlantic slave trade in 1792, but didn't actually abolish slavery until 1847, according to the museum.
This project was carried out by the museum's new research center, Njord, which plans to excavate several more Danish shipwrecks around the world.