"Useful" friendly fire !!!
Around the 10th of October 1943
Wensleydale was ordered to first find and then escort the Free French Submarine Minerve (P26) back to port. Ken England remembers that "the submarine was transmitting the morse letter 'A' on a known frequency and by manning our MF D/F set we were able to get a fix on the sub's position". This submarine had been a victim of 'friendly fire' and was unable to dive. A Liberator, piloted by Mick Ensor spotted a submarine about 300 miles west of Brest. The submarine was attacked with eight 5"rockets. One 25lb rocket entered the starboard side just below the external torpedo tubes. Two men were killed. One by the rocket head and another by a fragment of the pressure hull. The submarine was off course and not reported in the area. Pilot Mick Ensor (see Enser's Endevour, by Vincent Orange) was cleared of any blame. The damage to Minerve proved very useful to navy intelligence. Many photographs were taken of the damage, angle of entry etc. The projectile was said to be virtually undamaged, but was unfortunately thrown overboard as it was considered likely to explode.
Source:
http://www.hmswensleydale.co.uk/1943.htm