Itīs a boobie trap, a small merchant empty and heavilly scorted, the the u-boat attack tha "valuable" cargo and then the scorts start to chase the submarine.
Remember that is the Med and the things could be a bit difficult in this small sea.
i had a very interesting patrol with my IX-B boat, and was frequent see the luftwaffe in action near malta and some small convoys with troop transports and landing ships.
i remember when i destroy a troop ship with deck gun fire
