This German M4 Enigma machine is hugely rare. Why?
For a start it’s one of only a handful of specimens still in operational condition.
But the fact it has four rotors (rather than three) and used by U-boats (as opposed to the army) makes it the rarest variant of this infamous wartime encoder.
The M4's four rotors made it particularly tricky to crack
Sotheby's explains: “Multiple M4 Enigmas were deployed with each U-boat and support ship, and the majority of these were lost when their boats were sunk in combat or scuttled by their crew at the end of the war.
“Furthermore, German Enigma operators were under strict orders not to allow the enemy to capture any Enigmas; this meant that many Enigmas were stripped of their rotors and destroyed, with many thrown into lakes or oceans to hide any remaining parts.”
The M4 was used aboard the U-boats that terrorised the Atlantic during the second world war.
Its four rotors add an extra layer of complexity to the cipher. Enigma enabled the Nazis to broadcast coded messages without fear they would be intercepted.
However, they reckoned without the extraordinary genius of British computer scientist and mathematician Alan Turing.
While standard Enigma machines (in good condition) usually sell around the $40,000-60,000 mark, the M4 is in a league of its own.
The record is $547,500, set at Christie’s earlier this year.
This one is expected to make up to $500,000 when it crosses the block at Sotheby's New York on December 12.
We have a signed photograph of Britain’s wartime prime minister Winston Churchill for sale.
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