U-boat Archive - BDU KTB PG30285

F.d.U./B.d.U.'S War Log

16 - 31 March 1941

PG30285

Date	Position, Wind, Weather
and	Sea State, Illumination,	Events
Time	Air Pressure, Moonlight etc.



		16.3.			U 552 put into St. Nazaire. The Commander carried out his first operational trip with the new boat extremely well. Owing to numerous torpedo failures, the total result is only two steamers of altogether 13,000 GRT.

					Convoy U 106:
					U 106 maintained contact until 1056. From a U-boat warning at 1700 in EJ 69, it was conjectured that there was a least one boat in the area at this time. U 105 reported being in the convoy area.

					Convoy U 110:
					U 99 requested beacon signal from contact; it is therefore in the immediate vicinity.
					U 110 temporarily lost contact between 0205 and 0405 and then remained with the convoy until 0810 which was reported to consist of 15 ships and two destroyers. At 0830 the boat reported breakdown and requested a relief contact boat. For the time being contact appeared to be lost. In the meantime U 74 which was to relieve U 95 as south weather boat, reported its position as AM 11; far to the north, therefore, and in the vicinity of the convoy. This boat was also detailed for operations on the convoy. The reasons for not carrying out the order to relieve U 95 will be examined later. At present the following may be presumed to be in the convoy area. U 110, 99, 37, 100 and 74. At 1220 U 37 sighted the enemy in AE 8793 and sent beacon signal. At 1720 U 110 was again up to the convoy and at 1920 U 99 reported on request that it was in contact with the convoy. During the course of the evening a wireless message was received from U 37, reporting having been rammed beneath the surface. It received orders to return.

		17.3.			U 48 put out of St. Nazaire for the operational area.

					Italian U-boats are to be detailed temporarily for duties as weather boats, as our own boats are lacking. On the whole, the reports received are prompt and adequate.

					Convoy U 106:
					U 106 regained contact at 0700. No further messages were picked up during the day.

					In the evening further messages were received; according to these U 106 was still up to the convoy, while U 105 lost contact at 2209.

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Date	Position, Wind, Weather
and	Sea State, Illumination,	Events
Time	Air Pressure, Moonlight etc.

Recent messages from the boats reporting numerous unexplained failures, and surface runners, give rise to deep anxiety as regards the torpedo question. The following report thus:

a)	U 37, 9 unexplained misses and failures between the 8 and 10.2.
b)	U 107, 3 unexplained failures and a surface runner between 3 and 23.2.
c)	U 69, 3 unexplained failures and two surface runners between 12 and 24.2.
d)	U 97,5 unexplained misses on 24.2.
e)	U 73, a surface runner on 24.2.
f)	U 552,7 unexplained failures on 23.2.
g)	U 147, 2 unexplained misses at the end of February.

After a thorough examination of the existing battle and firing conditions on the return of the boats, and on the grounds of my personal knowledge of the capabilities and achievements of the Commanders, I am convinced that for the most part the misses referred to were simply failures. The Torpedo Inspection (Department) and Torpedo Ordnance Department have so far given no explanation for the torpedo failures. That these failures should suddenly appear after an uneventful six months in torpedo situation, must in my opinion, be significant.

As all the boats concerned, with the exception of U 37, were fitted out in home waters during the cold weather, the suspicion that the low temperature was in some way responsible, may not be unfounded.

I requested Professor Cornelius to come to Lorient for further enquiry and an intensive examination of the situation on the spot. Boats putting out from home waters have received orders to maintain and check torpedoes with particular care.

Fitting out depots have received instructions not, if possible, to give boats torpedoes which had been exposed to extreme temperatures after ranging. Recently received reports of successes from boats fitted out in Lorient stress the observation that the torpedoes belonging to these boats are in order. As a conclusion to the inquiry made by Professor Cornelius in conjunction with the Director of Torpedoes, Lorient, a conference took place today at which the Inspector of Torpedoes was present.

The inquiry has not resulted in an exact confirmation with regard to the cause of the failures, however the material available was examined and put in order, so that practical tests for the discovery and the circumventing of the cause may be started upon. There is,

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Date	Position, Wind, Weather
and	Sea State, Illumination,	Events
Time	Air Pressure, Moonlight etc.



					however, complete agreement that torpedo failures are the cause of the increased number of misses by U-boats from German ports, and that B.d.U.'s conjecture that the cold had influenced this, was the most likely explanation. The question arises whether the oil used for torpedoes is cold resisting. B.d.U. must demand that the Torpedo Technical Department must test the torpedo in all conditions it is likely to experience (also the effect of cold), before it is used in action. It must not be, in this connection, that boats in action take the initiative, after a number of valuable enemy ships have been missed.

		18.3.			Convoy U 110:
					At 0321 U 110 reported the convoy changing course to the SE. At 0503 the boat reported that the convoy had scattered. Contact was not reestablished, even with a section of the convoy. The attack therefore came to an end. Apart from U 110 which reported the sinking of two tankers, no reports of successes were received from the boats. Radio Intercept Service reported the torpedoing of three ships. Boats were requested to report as soon as circumstances allow.

					Convoy U 106:
					It may be presumed from the two U-boat warnings, that at least two attacks took place on it on 17.March. At 0203 U 106 lost contact. U 105 was also silent and was therefore probably not on the scene. In the evening both boats received instructions to proceed to the south if they were not in contact with the enemy.

					UA has put into Lorient. One steamer of 8,000 GRT was sunk. The Commander was forced to break off operations prematurely as the boat sustained heavy damage in a depth charge attack and further operations were complicated. He carried out duties well and with determination.

					There was a conference - B.d.U. with the newly appointed Fliegerführer Atlantic; KG 40 (previously operationally under B.d.U.) and other Luftwaffe Groups for operational duties over sea are now under him. Questions of cooperation and the form it should take in the near future were clarified.

					U 69 put out of Lorient and U 551 out of Bergen for the operational area in the Western North Channel.

		19.3.			It appears from a message from U 99, picked up by U 37, that the crew have been obliged to abandon the boat and scuttle it.

					The lack of any kind of news of U 100, in spite of repeated requests, since the passage report from the North Sea, also increases the anxiety with regard to this boat. At the moment, I can only reckon with certainty on three boats in the northern area.

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Date	Position, Wind, Weather
and	Sea State, Illumination,	Events
Time	Air Pressure, Moonlight etc.



					U 76 put out of Kiel for the operational area.

					U 95 has put in to St. Nazaire from a long-distance voyage.
					Convoy U 106:
					U 106 reported the sinking of three steamers of approximately 21,000 GRT from the convoy and two isolated steamers of altogether 14,316 GRT. U 105 regained contact with the enemy at 0240 and was again beaten off at 0306. It may be assumed from Radio Intercept reports that it had sunk 2 steamers, including a 6,000 ton tanker. Contact was again temporarily lost during the day and was reestablished by U 106 at 1602. The boat reported that a battleship of the Malaya Class was acting as escort. This lengthy pursuit of the enemy makes it questionable whether my intention to permit both these boats to replenish supplies from ship 41 on about 25 March can be carried out. It is possible that by reason of insufficient fuel, the boats could no longer return from so far south. A forewarning for the replenishment of supplies in Culebra is therefore necessary.

					A message from U 124, the first boat to take on supplies from the ship on 15 and 17 March, has not yet been received.

					Convoy U 46:
					Aerial reconnaissance reported an outward-bound convoy consisting of more than 25 ships and 6 destroyers, course 270 degrees, in AM 4649, at 0835. U 46, outward bound in the vicinity, and the Italian boats to the west have been informed of the enemy sighting.
					U 46 gained contact with the convoy at 1100, and maintained it until 1945. None of our own boats were in the area. 4 Italian boats were detailed for action, also several aircraft which are to be directed to the convoy by the boats.

					A further convoy, putting in to port, was confirmed by the Luftwaffe at 0905 in AM 4616. There are no boats available for deployment.

					A third convoy was also reported by the Luftwaffe at 1130 in AM 3364. Course 270⁰. An immediate U-boat operation is impossible here too. After repeated consultation with the Fliegerführer, an intensified air reconnaissance was planned for the following day in the convoy area, which can be reached by then, while the available U-boats - 3 altogether - are brought up, far enough to the west however, so that they are certain of being ahead of the outward-bound convoy when the Luftwaffe reconnoiters the area.

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Date	Position, Wind, Weather
and	Sea State, Illumination,	Events
Time	Air Pressure, Moonlight etc.

20.3.

U 97 put out of Lorient for the operational area.

U 124 reported having replenished supplies from Ship 41. The boat is returning to the area west of Freetown as instructed.

The Commander of U 95 reports having sunk 5 steamers of altogether 33,000 GRT. Duties well and efficiently carried out, result very gratifying.

Convoy U 106:

U 106 continues to send messages at long intervals. According to this boat the enemy deviated first in a northwesterly, later in a southwesterly direction.

U 105 appears to have kept up with the enemy, as it reported at 2358: "contact lost, request beacon signal".

U 46, which lost contact with its convoy the previous evening, reported its position in the forenoon. From this it would appear not to have found the convoy again. The Italian U-boats have presumably also passed by. Altogether 2 FW 200s from Stavanger and 1 FW 200 from Bordeaux were sent out against the north-bound convoy confirmed by the Luftwaffe at 1130 on 19.3.

The aircraft were not able to locate it in the medium visibility. The three U-boats brought up to action positions to the east, were left in their positions until evening, then, when it was no longer considered possible to intercept the convoy by day, they were ordered, together with the remaining boats still coming up, to the following operational areas:

a)	Lines between 10 and 19⁰ W. in the vicinity of the grids:
	U 551	-	AE 84
	U 74	-	AE 87
	U 98	-	AM 11
	U 46	-	AM 13
b)	U 110 west of Ireland as far as 25⁰ W., research into traffic to Reykjavik.
	U 48	-	grid AE 74 and 75 and 77 and 78.
	U 69	-	grid AL 12 and 14 and 21 to 24.

21.3.

At 1201, U 69 outward bound, reported a convoy in sight in AL 8822. Easterly course. U 48 also outward bound in the vicinity was detailed for action as were 4 returning Italian boats. It appeared possible from the probable

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Date	Position, Wind, Weather
and	Sea State, Illumination,	Events
Time	Air Pressure, Moonlight etc.



					positions of the boats that the convoy could be reached before nightfall. The medium visibility reported from the area made things more difficult. U 69 lost sight of the enemy at 1415, regained it temporarily at 1840, reported being beaten off, and finally lost contact.

					The Naval War Staff announces that from now on, only one weather report from a German boat between 0200 and 0500 and from an Italian boat towards midday is necessary.

		22.3.			Convoy U 106:
					While both boats were still up with the convoy, U 106 reported at 0212 having expended all torpedoes below deck and at about the same time, U 105 reported only having one more stern torpedo below deck. The boats received orders to reload torpedoes, weather permitting, and to keep up with the convoy, or to proceed to the assembly point to replenish supplies from the store ship. The boats reported being unable to reload. Replenishment of supplies is planned for 29 March. Operations on this convoy are therefore broken off. The following have been sunk according to messages received:
					U 105 - 6 steamers of altogether 41,000 GRT
					U 106 - 5 steamers of altogether 36,000 GRT
					A total of 11 steamers, of altogether 77,000 GRT.
					An excellent performance by both boats, and an exemplary instance of the increased possibilities, resulting from the cooperation between several boats.

					U 48 and U 69, which have apparently not regained contact with the enemy, received orders to proceed.

					U 52 has put out of Lorient for the operational area. It had to return owing to engine trouble.

		23.3.			U 110 reports damage from tube prematures, which restricts submerging. It has started upon the return passage to Lorient.

					t 1238, U 97 reported a convoy in BE 2242. Southwest course. No further messages have been received.

					A japanese Naval Commission is visiting Lorient. Inspecting several U-boats. Lecture on German U-boat warfare.

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Date	Position, Wind, Weather
and	Sea State, Illumination,	Events
Time	Air Pressure, Moonlight etc.



		24.3.			U 46 reported in a short message that no traffic had been observed. The remaining three boats in the northern area, U 74, 98 and 551 were requested to report on traffic in a short signal. U 74 and U 98 reported absence of traffic.
					No message has been received from U 551.

					As, in the last few days altogether 4 convoys as well as isolated vessels have been confirmed in the area S.W. of the Northern Channel by aircraft and U-boats, while merely a few isolated steamers have been intercepted in the north since 18 March, the question arises as to whether it is right to leave the majority of the boats there. The enemy has possibly diverted his traffic and transferred it to the south. Previous experience has shown that a sensational transfer of merchant shipping routes is unlikely. It has been proved time and time again, that the English stick to the same areas, in spite of heavy losses. I therefore intend to wait another two days with an entirely new distribution of operational areas, and extensive air reconnaissance is to be carried out in the whole area to the north, west and southwest of the Northern Channel, beforehand.

					U 101 put out for the operational area but was forced to return owing to engine trouble.

		25.3.			No message from U 551.

					U 76 has had to turn back owing to technical difficulties and put into Bergen for repairs in the evening.

					Owing to the poor visibility anticipated on 26 March - the day I had planned for the large-scale aerial reconnaissance - I have decided to order the redispersal of the boats (intended for the 27.) for today. I am strengthened in this decision by the consideration that it is inadvisable to remain in an area in which heavy losses, the reason for which has not yet been fully explained, appear to have occurred within a short period. The following operational area are ordered:
					Channels between 19 and 25⁰ W in the vicinity of the grids:
					U 48 - AE 78; U 69 - AL 22; U 74 - AL 24; U 98 - AL 26; U 46 - AL 28; U 551 - AL 02 further; U 97 - the grids AL 50 and 60.

					U 73 has put out for the operational area west of the Northern Channel.

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Date	Position, Wind, Weather
and	Sea State, Illumination,	Events
Time	Air Pressure, Moonlight etc.



		26.3.			Air reconnaissance, reinforced by five aircraft, confirmed a small heavily escorted convoy on a course of 155⁰, S.W. of the Faroes (AE 9857), and an isolated steamer on a course of 145⁰, N.E. of the Rockall Bank (AM 1699). On the previous day another steamer was sighted in AM 3110, while on both days no traffic was observed S.W. of the Northern Channel. Even if this reinforced air reconnaissance is defective, events prove that the area N. and N.W. of the Northern Channel is being navigated.

					U 76 has put into Bergen.

		27.3.			U 52 and U 101 put out of Lorient for operations in the area west of the Northern Channel. In accordance with the planned extension of the blockade area round England, I have proposed to the Naval War Staff a considerable extension of the U-boats operational area. I do not see that the possibility of U-boats encountering our own surface craft is an obstacle to the extension. Experiences in this area strengthen this conviction. The Naval War Staff have agreed.

		28.3.			Aerial reconnaissance has confirmed several isolated steamers on a westerly course in the area S.W. of the Faroes to Rockall Bank. Otherwise nothing to report.

		29.3.			U 48 reported a convoy on an easterly course in AE 7844. The boat maintained contact until 1522 when presumably, owing to strong escort encountered, either on the spot or in the vicinity, it was lost. 8 torpedo-boats were reported. The torpedoing of four steamers of altogether 24,500 GRT was reported by Radio Intercept Service.

					U 69 sighted an outward bound convoy in AL 1282 at 1254, steering first on a west, then on a northwesterly course. The north boats received orders to operate according to circumstances, on one of the two convoys for the time being; all things being equal, the outward bound convoy was to be chosen.

					I consider the escort belonging to U 48's convoy too strong for the at present, extremely inexperienced boats.

					U 69 kept up with the convoy until 1930. From wireless messages and situation reports, it appeared that U 48 and U 46 were operating on the convoy, U 98, on the other hand, had sheered of far to the east in an attempt to intercept U 48's convoy. The torpedoing of an unidentified steamer in AL 3171 reported by the Radio Intercept Service,

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Date	Position, Wind, Weather
and	Sea State, Illumination,	Events
Time	Air Pressure, Moonlight etc.



					can probably be attributed to U 98.Air reconnaissance sighted another convoy in AM 5420. Its position is still so far east, that for the time being U-boat operations do not appear worth while. I therefore propose a strengthened air reconnaissance for tomorrow, and to move up the two boats in question, U 73 and U 97, to the east.

					U 76 has put out of Bergen, U 94 out of Lorient, for operations in the area west of the Northern Channel.

					U 107 has put out of Lorient for the operational area west of Africa.

		30.3.			U 52 was forced to turn back owing to damage to the engines.

					U 69 probably pursued its convoy longer than was implied from wireless as, though no enemy reports were received from it after 1930 yesterday, a report of having lost contact was received at 1300 today. Also the weather report U 98 was to have sent has not been picked up. It appears that receiving conditions have been exceptionally poor during the last twenty hours.

					U 69 reported having broken off the chase at 2000. THe boat sank a steamer of 7,000 GRT and had 5 failures with electrical torpedoes. U 46 sank another isolated steamer of 6,000 GRT roughly the same area. This possibly belonged to U 69's convoy, which according to previous experience, must have dispersed on about 25⁰ W.

					Air reconnaissance again confirmed the convoy reported on 29 March, the U-boats U 73 and 97 stationed at a distance of about 150 seamiles ahead however, have not approached.

					Owing to very bad reception it is impossible to judge whether the boats have heard the aircrafts bearing signals or not. The number of convoy escort vessels was given as eight. According to another aircraft report five destroyers, probably a chaser group, are in the vicinity. Altogether, it appears from recent events, that there is strong convoy protection and U-boat escort. I have therefore decided to withdraw the boats further to the west. Even if the traffic bunching is less there, one can expect a considerably greater freedom of movement for the boats, owing to the lack of defence and surveillance. In any case, losses in the last month have been so high and the reason for them so obscure, that at the moment it appears inadvisable to remain in the area.

					New operational areas assigned:
					U 48 - grid AK 23 to 33
					U 69 and U 98 - grid AK 26 and 36

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Date	Position, Wind, Weather
and	Sea State, Illumination,	Events
Time	Air Pressure, Moonlight etc.



					U 46 - grid AK 28 and 38
					U 74 - grid AK 39 and AL 19
					U 97 - grid AK 63 and AL 42

		31.3.			Aircraft again established contact with the convoy confirmed on 29 and 30.3. COnvoy position at 0930, AL 6582. The aircraft was forbidden to attack and was to attempt to shadow unobserved. This it was unable to do, however, it was sighted by a convoy unit, which reported the convoy position in AL 6887. The difference in fix amounted to about 70 seamiles. It was thought that the convoy units report might very well be a reference point, a frequent surmise. However, as a second aircraft reported the convoy in AL 9136 at 1230, and the convoy unit reported the second aircraft in AL 9211, this last position can be taken as certain. The first aircraft's fix then was 70 seamiles out. U 73, U 97 and U 101 were detailed for action. These boats were in a favorable position about 100 to 120 seamiles ahead of the convoy. The aircraft sent bearing signals which should have been picked up by the U-boats and reported with their positions to act as check on the convoy position. No messages have been received. There was no contact with the enemy. In the evening the boats received orders to occupy their operational areas. U 94 and U 101 received grid AK 02 as position, U 76 the grid AL 15.

					U 98, from which no message was received for several days in spite of repeated requests, sent a position report.

					U 106 reported having carried out replenishment of supplies.

					In the light of experience, especially in the case of the last convoy reported by aircraft which was unable to remain unobserved, and the resulting strengthening of Fliegerführer Atlantic's conviction that an unobserved shadowing is impossible with the type FW 200, I have decided to give the aircraft in general freedom to attack. I hope in this way to cause the enemy to report on the air attack - from which the position may be obtained by the Radio Intercept Service.

					This had in fact happened twice today, and once previously.


					(Signed): DÖNITZ

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