150km off Plymouth 1940. WO reported a British Cargo ship 2,500 meters off our port side. Said ship immediately opened fire on us with a stern gun. I went to the tower and immediately ordered a course change to put a bow profile to the merchant, which continued to fire. I ordered a crew on deck to mann the deck gun. The crew consisted of two qualified PO's and a seaman as ammo handler. I ordered the crew to take out their deck gun. Our first two rounds hit the deck forward of the gun. We then took a round to our bow which did minor damage to our forward tubes. Our third shot missed probaly due to the hit we took. Our forth and fifth shot took out their deck gun. After that it was all us. She went down nine rounds later. We observed life rafts and approached them slow with both AA's manned. We provided a compass, tobacco, water and old rations to the suvivers. Due to the fact that we were close to the English Coast and that she had time to get off an SOS we immediately dove to 30m. At 30 I brought out the last of the beer and we toasted the lost souls. We are all brothers. We surfaced two hours later and repaired damage.