In patrol 8 I encountered 3 unescorted small merchants and did not want to waste torpedoes on them. The one at the back was a neutral, first 2 British. So I sneaked up behind them with the neutral providing cover from their cannons. The neutral got hit by its "friends" several times. I could now and then swerve to take shots with the deck gun, eventually sinking the 2nd ship. Now I left the cover of the neutral and pursuit the first merchant but with the neutral behind me. I took some damage but nothing too serious. The neutral was sunk by the British merchant, hey not my fault
Obviously I also sunk the British merchant.