Hmmm... Interesting. Too bad there is no additional data on it.
But I found out about another two (this time an u-boat actually sinking submarines):
On 10 April 1940 U-4, a Type II boat under the command of 25 year old Hans -Peter Hinsch sank the 1100 ton British submarine Thistle off Stavanger Norway. Thistle was the first submarine confirmed as being sunk by a U-boat and was the only Allied warship sunk by U-boats during the Norwegian campaign.
1 August 1940 Wilhelm Rollman skipper of U-34 a Type VIIA boat sank the British submarine Spearfish while returning to base with his last torpedo, there was one survivor. This was in Norwegian waters also.
Anyway, let's not hijack this poor man's topic...
