The Nazis' Biggest Warship Is Still Messing With Trees In Norway


Tom Hale


Tom Hale

Senior Journalist

Tom is a writer in London with a Master's degree in Journalism whose editorial work covers anything from health and the environment to technology and archaeology.

Senior Journalist

Bombs exploding around Tirpitz during an attack on the battleship in April 1944. Imperial War Museum Collections

Tirpitz, the Nazis' biggest warship, was a thorn in the side of the Allies during World War II. Even after the British Royal Air Force managed to sink it in 1944, the battleship continued to raise hell... on Norway's forests.

Tirpitz, along with her sister ship Bismarck, was the largest battleship ever built by Germany. Despite its ferocious size, the 251-meter-long (823-foot) battleship actually saw little action in the war because the Allies were hell-bent on trying to destroy it. At the time, Winston Churchill said that “no other target is comparable to it.” Faced with this threat, it spent much of its time hiding in the fjords of Kåfjord in northern Norway inside a thick cloud of artificial fog created using chlorosulfuric acid.


New research, presented this week at the European Geosciences Union (EGU) General Assembly in Austria, has shown that the damage from the chemical fog can still be felt in the pines and ferns of Norway. You can look at a tree’s rings and learn a lot about its life, such as its age and even the environmental conditions present when it was growing. It’s no surprise then that the legacy of the chlorosulfuric acid can still be seen in the forests surrounding the fjords.

"The story was in the tree rings," Claudia Hartl, a researcher at Johannes Gutenberg University in Germany, told AFP. "We got back to the lab and measured the tree rings, and saw that they were very narrow – in some cases nearly absent – for 1945.”

Image of Tirpitz. Published by the Division of Naval Intelligence of the Navy Department of the United States, 1942

The researchers are calling this method “warfare dendrochronology” – the study of tree rings to uncover the story of a human war. Some trees were found to have not grown for nine years after the war. Many others were found to have unusual growth rings for at least 30 years after 1944. It’s likely that the chemical fog stripped the pine trees of all their needles, thereby impairing their growth for a number of years.

When the tree experts first came across the peculiar features, they believed they might be the result of an insect pest, but a discussion with local scientists revealed that the fjords of Kåfjord were actually a regular hideout of Tirpitz, whose crew used this bold fake fog technique to camouflage themselves. 


A sneaky technique it may be, but eventually, their luck ran out. In November 1944, after years of repeated attempts, the British found and sunk Tirpitz. A fleet of British Lancaster bomber aircraft showered the ship with bombs, quickly capsizing it. Around 1,000 are believed to have died in the attack.


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