In May 1645 Swedish navy ships were in the harbour of Wismar. At an inn, some Swedish sailors spotted a man that they recognised from Lübeck, where he worked for the Danish king. Carl Gustaf Wrangel had him arrested. He claimed to be a cheese vendor and that his name was Hans Grefft. Grefft’s trunks were searched and gun powder, sulfa, hay and two small time fuses in metal casings were found.
Grefft was not cooperative, so he was put under ”painful interrogation” and eventually confessed that the time fuses were intended to be placed inside trunks with flammable material on board two Swedish ships.
You can see one of the time fuses here. It has a wheel lock construction and will start a fire by igniting gun powder.
No ships were ever put in flames by these time fuses, but Hans Grefft himself was burnt in October 1645.
Text: Andreas Olsson
Scan: Erik Lernestål