APPENDIX "E"                                                                                                      S E C R E T
  
   
          Ar 0635Z on 13th March, 1944, Fortress, R/206, was proceeding to datum for A/S Patrol, having been briefed on position of attack by Wellington, B/172, at 0151Z the same morning, when five Mark II Marine Markers were sighted 15 miles distant on the starboard bow.  "R" proceeded to investigate and circled at 300 feet, but cloud down to 500 feet obscured the moon and made observation difficult.  "R" attempted to inform base of marine markers by W/T, but could not get message through.  "R" dropped one further marine marker alongside and continued to circle.  Dawn broke at approximately 0715Z but nothing could be seen except the marine markers until, at 0740Z, a U-boat surfaced about two miles North of the markers on a heading of 270° (T) and settled down to a speed of 5 knots.  The U-boat bore 030° green 4 to 5 miles from the aircraft, which was then at 500 to 700 feet.  Captain of "R" executed tight turn to port intending to get out the Flash Report and crew at action stations and attack from U-boat's starboard bow.  When "R" had turned through about 270° the U-boat took evasive action by turning to port presumably trying to bring rear armament to bear.  As "R" was completing the 360° turn, U-boat opened fire with a medium calibre gun forward of the conning tower.  U-boat's action convinced Captain of aircraft that U-boat intended to remain on the surface, so he circled around the U-boat at 1,500 feet and 2 to 3 miles distance, just out of range of U-boat's guns, switchbacking and trying to get a Flash Report through to base.  At about 0755 the U-boat fired a red flare followed at intervals of one or two minutes by two more.  "R" replied with a two-star red-green cartridge, which had the effect of temporarily silencing the U-boat's guns, so "R" edged closer to the U-boat within the range of the U-boat's guns, and although the Flash Report had not been acknowledged and the U-boat re-opened fire with both the forward deck gun and probably 20 mm. cannon fire the rear of the conning-tower after an interval of four or five minutes, the Captain decided to attack before it was fully light.  His intention was to attack from the bows to stern of U-boat, but the U-boat was out-turning the aircraft to port in a circle of 200 to 300 yards diameter, and he was forced to make an attack from the U-boat's starboard beam using diving turn from 1,000 feet as evasive action.  During the turn the U-boat was firing presumed 20 mm. guns from bandstand, most of the fire appearing to pass to port and below the aircraft.  "R" replied at an initial range of 1,000 yards with nose gun and mid-upper turret, strikes being observed on the conning-tower.  "R" straightened up for the final attack at 300 yards range, when the U-boat's flak appeared to be all round the aircraft though it was never actually hit.  The Captain attacked from 40 feet tracking over the U-boat immediately forward of the conning-tower.  "R"'s rear gunner fired continuously at the U-boat's conning-tower from the time that he first saw it till the explosion of the depth charges and claims hits.  The port beam gunner fired into the depth charge plumes.  The rear gunner states that the depth charges exploded one to starboard and three to port of the U-boat, and several members of the crew confirm that the U-boat was entirely enveloped in spray from the plumes.  The U-boat settled by the stern for 2 to 3 seconds after the attack and then the bows lifted clear of the water and U-boat slid underwater at an approximate angle of 35° to 40°.  Within 2 or 3 minutes after attack, dark colored oil had spread in two joined irregular oblong patches approximately 500 yards long with 2 small black patches approximately 20 yards across in the middle.  Large air bubbles 2 or 3 feet across started immediately after the U-boat submerged and continued for 2 to 3 minutes.  Both oil patches and air bubbles appeared over the position of the attack.  "R" continued circling at 1,500 feet taking photographs and dropping a marine marker.  During the entire 5 hours and 13 minutes after the attack the oil patches showed no signs of movement.  At 1030Z "R" started W/T homing procedure on instructions from base, which was presumably instrumental in guiding Fortress J/220, and Frigate H.M.C.S. "PRINCE RUPERT" to the scene.  At 1318Z "R" having reached P.L.E., set course for base.  Twelve minutes later "R" was in communication with H.M.C.S. "PRINCE RUPERT" by R/T and fully informed her of the situation.  
     
 
S E C R E T