The spoils of a battle that gave hope to the Allies in their darkest hour will go on sale at a special auction next week.
In August 1941, Hans-Joachim Rahmlow, a novice German commander, surfaced in a Norwegian fiord with a seasick crew after failed attempts to torpedo Allied ships.
An Allied bomber hit the Nazi sub, which lost power and leaked. The young crew thought acid from batteries was mixing with seawater to create deadly chlorine gas.
Instead of diving to safety, they panicked and the Royal Navy captured the U-boat.
"It was a real coup for Churchill," Fenella Tonkin of Cordy's auction house says. "You imagine Churchill dancing with glee and Hitler having a complete tantrum."
Rahmlow's sword, with an 80cm blade and brass-bound leather scabbard, eventually passed into the hands of a Kiwi sailor, Captain Andre Douglas Holden, whose children have put it up for auction.
It is estimated the sword will fetch more than $10,000.
Artist Colin McCahon started Cordy's auction house in 1964 with friends Hamish Keith and Peter Webb.
The sword is just one item on offer in a 50th-anniversary auction this Tuesday.
Also included is an emerald and diamond ring valued at $22,000, clocks, silverware, rugs, furniture, paintings and a pre-European Maori hei tiki. John Weekes