Commander of Home-Based Submarines
Royal Navy
December 1940
Speaking as a man who has known submarines for years, due to my prior experience in World War I, I will make my recommendations regarding the problem of the German U-boat fleet in the Atlantic.
Simply put - we need to rethink our resource allocation regarding the Atlantic before the situation becomes unmanageable.
The "ten year rule", which bases our spending on the assumption that Britain will not have to fight a major war for ten years, has led to inefficient resource allocation. We have focused on our battle fleet, while neglecting the possibility that there would be an attack on merchant shipping. Most of our vessels are designed for coastal work, not convoy work, due to this misallocation.
The Town class, as well as the V and W class destroyers that we are repurposing for escort duties have too many guns, and cannot turn properly due to the length of their hulls, decreasing their maneuverability. Similarly, our aircraft are not trained for anti-submarine warfare, due to the Navy's prior focus on fighting a surface fleet instead of a fleet of U-boats. If we want to combat the U-boats, the Navy will have to expand its anti-submarine forces rapidly and immediately. We have been protecting our shipping with sloops, destroyers that are relics from the previous war, and aircraft that best belong in a museum.
The navy's anti-submarine measures also lacked foresight. They were created under the assumption that the enemy would adopt the same strategies. Our submarines are used for reconnaissance, and we withdraw them at night so we do not compromise our position. But it is unquestionable that the Germans are not using their U-boats for the same purposes. They have used their U-boats for the sole purpose of seizing their prey, and they do not withdraw at night, so they can lie in wait in the darkness. We have not developed any anti-submarine measures, since the Navy did not foresee the possibility that submarines could be used for the purpose of attacking shipping.
The Atlantic fleet has also been too dependent on ASDIC, and I believe that recent events have proved its unreliability. ASDIC seemed good in theory - a transmitter that sent an impulse through water, in order to detect submerged targets, seemed incredible at its time of inception. However, while the Defense advisory Committee placed all its faith in ASDIC prior to the war, ASDIC has had limited utility in this situation. The Navy failed to test it before the war, and have had no prior experience of ASDIC in non-controlled conditions. Any competent submariner could have told you that the difference in temperatures due to the depth of the water would affect the sound waves.
ASDIC's range is limited to 1500 yards, and it is ineffective in rough weather and at speeds above twenty knots. The night raids have hit us hard partially because of our reliance on ASDIC – it cannot distinguish between submarine and non-submarine targets, and detect surfaced U-boats. The only way of detecting a surfaced U-boat is by sight, but the dark night and the shadows of the ships in convoy have eliminated even that method. 60% of our convoys have been sunk at night. There have been a few near misses and narrow escapes from the U-boats, but these are mainly due to defective German torpedoes. We must act soon before the Germans can devise improved magnetic and contact firing pistols.
The Navy has been lax in our anti-submarine preparations, as pre-war preparations have focused on defeating surface forces and battle fleets. The assumption that U-boats would only attack by day has been proven false, and ASDIC has been proven to be unreliable. We are undeniably at a disadvantage, and we must reallocate our resources in the Atlantic campaign and reinforce the escort fleet to avoid utter failure.
If the Atlantic operations continue along these lines, Britain will lose.
