In 1941, Germany invaded Russia and decided it needed a presence in the Black Sea to harass Soviet shipping there. Unable to use the Bosporus, the only shipping route into the Black Sea, the boats were dismantled at Kiel and taken by canal to the Elbe, and upstream to Dresden.
Here, they were partly dismantled and taken by lorry to Ingolstadt, on the Danube, and then ferried downstream to the Black Sea and Constanta, where they were re-assembled.
When Romania switched sides the crews were ordered to scuttle out of sight of the Turks so the submarines’ locations would remain a mystery. Mr Kolay was helped by a map drawn by Rudolf Arendt, 85, the former captain of the U-23, showing where his crew came ashore.
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