This Canadian Creamery Butter tin comes from Colditz Castle in Germany. The tin was part of a Red Cross parcel, sent to Allied Officers imprisoned there during the Second World War. I acquired it at the castle museum in 1990, when they were raising funds to support their work.
Colditz was declared "escape-proof" by the German wartime command. They used it to house Allied officers who had escaped from other camps and were recaptured, or who were considered to be high escape risks.
The interesting part of the story for me is that, according to the museum curator, the tin is likely to have been used by would-be escapees when digging one of the two main tunnels out of the castle. Small sections of the castle's soft rock were first heated by candle-flame and then splashed with cold water to make it crack, and the debris was then scraped away.
Tins like this one were found when the tunnels were discovered by the prison guards. The tins and other detritus were left where they were, only to be discovered decades later when the tunnels were re-opened to see what was in them.