A Hellish Device

The story behind a 17th Century detonator

By Skokloster Castle

Field Marshal Wrangel (1662) by Matthaeus MerianSkokloster Castle

Based on a True Story

“Right Honourable Master, merciful and high ruling Chancellor of the Realm. Your Excellence have from my despatch on the 30th of April received my humble description of the present state. Duty compels me, Your Excellence, to disclose how, through the will of the All Mighty God, an important matter has been revealed…” (Letter from Count Wrangel to Count Oxenstierna, 1645)

The battle of Fehmarn (c. 1650) by Willem van der Velde the ElderSkokloster Castle

It all began with a splendid victory. Field Marshal Carl Gustaf Wrangel commanded the Swedish fleet at the Battle of Fehmarn in 1644. It was an intense battle. Almost the entire Danish navy was obliterated.

But it was a victory at a cost. The Swedish ships were badly damaged, and they took shelter in the port of Wismar for the winter. Wismar was for some months crowded with merchants, sailors and navy carpenters. One man singled himself out, however.

Harbour scene (c. 1615) by Adam WillaertsSkokloster Castle

Hans Grefft from Pomerania was “a frivolous man courting heinous and traitorous thoughts” masquerading as a cheese merchant. He was recognised by navy personnel in the taverns that he frequented as a Danish spy. Field Marshal Wrangel heard of his suspicious behaviour and had the man arrested.

Detonator (1640/1650) by unknownSkokloster Castle

Caught Red-Handed

In Grefft’s
lodgings two coffins were found containing hay, wood shavings, powder, sulphur, tar and
a clockwork ignition each. The would-be terrorist was interrogated “voluntarily at
first but, as this did not work, then with pain”. The General Clerk Antoni von
Rehnskiöld and Major Lorens Matsson attended the interrogation as

Question: Is this ordered in the name of the Danish King?

Answer: In the Emperor’s name, not the King’s.

Question: Who has planned it?

Answer: I was called to Wismar by a tall, corpulent man from Lübeck wearing grey, badly made clothes, grey hair and beard, staying with Jörgen Burchard next to the Blue Tower. I was asked to do a favour for 1 000 Daler. Thomas Ritter from Lübeck was the organiser.

Question: Where were you recommended to lodge in Wismar?

Answer: At the naval society but on arrival I went to the Klinkhammer. (Nick-name for the tavern the Forge owned by Hans Martens.)

Closeup of a Detonator (1640/1650) by unknownSkokloster Castle

Question: Name your accomplices.

Answer: A constable, no other in this town. One of the coffins was given by Joachim Schueman and a letter from Thomas Ritter. The second coffin came from David Macken together with yet another letter and a small coffin for the Three Lions [a man of war]. The other coffins were for the Dragon upon which Admiral Blume would have been.

Disassembled Detonator (1640/1650) by unknownSkokloster Castle

Question: Where were the time devices manufactured?

Answer: In Hamburg. By whom I do not know.

Inside of a Detonator (1640/1650) by unknownSkokloster Castle

Question: Have you had contact with the Danish officers imprisoned here?

Answer: I have not socialised with anyone at the Klinkhammer, but I did confide in a Lieutenant Jacob Baren, who advised me to not to proceed with the deed and draw misfortune upon myself.

Underside of a Detonator (1640/1650) by unknownSkokloster Castle

Question: Would you have persevered with this treason even if his Excellency the General would have been on board?

Answer: Yes, truly, yes.

Hans Grefft was found guilty by own admission and sentenced to be burnt alive at the stake. The sentence was executed in October 1645. As a memento Field Marshal Wrangel sent one of the time-devices to the Royal War Cabinet and kept one for his own armoury at Skokloster.

Credits: Story

National Historical Museums
Text and editing: G. Sandell
Photo: J. Mohr

All information is taken from a letter from Field Marshal Wrangel to Count Axel Oxenstierna, Lord High Chancellor of Sweden, 1645.

Credits: All media
The story featured may in some cases have been created by an independent third party and may not always represent the views of the institutions, listed below, who have supplied the content.
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