The NAVAL, MILITARY AND AIR SITUATION for the week up 12 noon March 28th,1940 as reported to the War Cabinet:
An unusual feature this week has been the successful attack on German merchant shipping off the Danish coasts by British submarines. No air attacks on shipping have been reported. The total loss of merchant shipping for the week is less than it has been for any week since the beginning of the year.
2. A strong force from the Home Fleet has been cruising in northern waters to provide support for the Norwegian Convoys and the Northern Patrol. On the 22nd and 23rd March a sweep into the Skagerrak was carried out by light forces, with the object of intercepting German merchant shipping. None was met with by these forces. Some success was achieved by our submarines working in these waters, details of which are given in paragraph 15 of this Resume, and the consequent interruption of the flow of German merchant shipping may account, in part, for the lack of success by our light forces.
3. Following indications of the presence of a U-boat in the Switha entrance to Scapa Flow, a section of the observation mines was fired during the early hours of the 22nd March. Subsequent examination by divers, however, failed to establish that a submarine had been there.
Early on the 22nd March H.M. Trawler Loch Assater swept up three mines in her trawl, to the north-eastward of Kinnaird Head. The third of them exploded and the trawler sank. The crew was rescued, but the Skipper and two hands were wounded. It is probable that these mines came from a deep minefield of our own in this area.
Three French submarines have arrived at Harwich to co-operate with our submarines in the North Sea.
4. On the 27th March a report was received from Oslo that a German submarine had grounded off Mandal, South Norway, and had re-floated later with one engine damaged. British submarines on patrol were informed and an air search was arranged on the 28th; subsequently information was received that the submarine (U. 21) had been interned by the Norwegians.
13. The [following] sketch shows the extensive system of searched channels which are searched daily if the weather allows.
14. Eight magnetic mines were intentionally exploded in known dangerous areas during the week. Six of these were exploded east of the Tongue light vessel, and one in the Sunk Area. The other mine was exploded by a skid in the Falmouth approach.
A large number of explosions were reported on the 25th March in the Thames Estuary, off Southwold, and off the Humber. It has been suggested that these mines were fired by very intense magnetic storms and the Astronomer Royal is investigating this possibility.
German Merchant Shipping.
15. On the night of the 21st/22nd March, S.S. Heddernheim (4,947 tons) was intercepted 8 miles East of the Skaw by H.M. Submarine Ursula. After the crew were safe in their boats, in flat calm weather, the ship was torpedoed.
Two nights later H.M. Submarine Truant intercepted the S.S. Edmund Hugo Stinnes (2,129 tons). She was outside Danish territorial waters, but entered them while under gunfire, where she appeared to be scuttled and abandoned, so was finished off by a torpedo. The master was taken prisoner by Truant.
MILITARY SITUATION. Western Front.
18. There has only been local activity, during the weet—German raids on Allied posts have on every occasion been repulsed, and prisoners captured by British and French. The B.E.F. has started to take over a further portion of the front, and is extending its left to include Bailleul. This extension of the flank will be completed by the 30th March. Headquarters III Corps and certain Corps Troops are now in France, and the move of the 44th Division to France began on the 27th March.
AIR SITUATION. Royal Air Force Operations. Bomber Command. Reconnaissances to Establish Results of Sylt Raid.
26. Daylight reconnaissances were again despatched on the 22nd, 23rd and 27th March, but weather conditions made observation and photography difficult. Of two aircraft sent out on the 27th March, one failed to return and is believed to have been shot down by a formation of three Messerschmitt 109′s which were seen to attack it. The other aircraft flew at high speed past the seaplane bases at Hornum and List, at distances of 1 and 3 miles respectively; no special evidence was seen of substantial damage to the main structures.
Photographs, however, revealed that the landing stage at the end of the small pier at Hornum had disappeared. They also showed one vessel in harbour with a large crane I amidships; probably a merchant vessel converted for catapult use. Seaplanes were observed moving on the runways and taking off, and a train was seen crossing the Hindenburg Dam. The aircraft also saw thirteen enemy fighters in the air, and was attacked from astern by three of them, which it evaded successfully in cloud.