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Mine Situation in Biscay: |
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I. |
The charts captured in Nazaire in the English destroyer Campbelltown, with the mined areas entered, confirm the necessity of abandoning the approach routes to Brest (Sternbild and Rippenbruch). This had been done some time before. The arrangement of the minefields also gives rise to the suspicion that the enemy had begun to cut off the Biscay methodically, starting from the north, by minefields along the 200 meter line. As the northern approach routes to Lorient (Jugend Liebe and Bogenlampe) had been closed owing to enemy mines laid closer to the coast, the Brest boats had: |
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1) |
to use the south route to Lorient (Cedernland) and then proceed along the coast on route Rosa, i.e. cover a longer distance through inshore waters endangered by mines and S/M's and |
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2) |
to put into Lorient as an intermediate port, so that the additional danger from a/c was eliminated. During daylight they lay in Lorient and continued their passage to Brest during darkness. The consequent loss of half a day, outward and inward bound, had to be accepted. |
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II. |
All U-boat traffic was now crowded onto the 2 routes Tannennadol and Uhunest, which lie close together and lead to the center of the Biscay coast, as the routes south of these, leading to Pallice and to the Gironde could not be constantly checked for mines, owing to F.O.I.C. Western Defenses' lack of forces, and were therefore closed. This restriction to 2 routes means: |
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1) |
A longer passage in inshore waters for all boats which belong to Brest, Pallice and Bordeaux. |
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2) |
Crowding together makes things easer for enemy S/M's and a/c and raises the effectiveness of mining operations there. |
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3) |
The basic principle, to allow only incoming or only outgoing U-boats or only minesweepers along one route at night, has in some cases to be disregarded, which means danger for the U-boats. |
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4) |
If the principle in para. 3) is adhered to, which is essential on dark nights, then F.O.I.C. Western Defenses' few forces are further restricted in their movements, to the disadvantage of the safety of the U-boats. |
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5) |
There is danger that the enemy will lay minefields in inshore waters which are not checked by us without our noticing it. It is only a short step from there to closing the comparatively narrow checked emergency route in the center and Biscay suddenly being really cut off. |
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III. |
On 20 April route Burggraf was declared in use, and this meant a certain relief of the 2 central routes, as the italian boats were now given a direct route and Pallice boats could be escorted along this. They still had to go out of their way slightly compared with the original direct approach route to Pallice |
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This relief, which was comparatively slight, was more than cancelled out on 26.4 by the closing of route Tannennadel, which included Cedernland almost all the Atlantic boats, i.e. Brest, Lorient, and Nazaire boats, were now directed to route Uhanenst, |
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