The revelations about the catastrophic fates of these three U-boats after all these years may be new but there has been no secret about the laying of 'Deep Trap Minefields' off the north coast of Cornwall.

According to the Naval Staff History of British Mining Operations 1939-1945 Vol I, the Admiralty issued a policy signal to CinC Western Approaches on 15 Nov 1944 stating that:

"Further consideration has been given to the relative importance of anti-U-boat minefields in the NW and SW Approaches. Routing of ocean convoys south of Ireland not only renders this the more attractive area but U-boats' course of action can to some extent be anticipated. In the NW Approaches, minelaying operations must follow rather than anticipate U-boat activities... Consider therefore as a matter of policy that minelaying operations should be concentrated in the SW Approaches."

Between 29 Nov 1944 and 3 Jan 1945, the minelayers HMS Apollo and HMS Plover laid over 1,200 Mk XVII moored mines in 10 'deep fields' across the coastal convoy route along the north coast of Cornwall in Operations "HW" and "HY". Moored mines were used because ground mines sensitive enough to catch slow-moving U-boats would also have posed a threat to Allied surface ships.

This was only the start of more intense laying of 'Deep Trap Minefields'. By the beginning of 1945 there had been a steady increase in the number of schnorkel-fitted U-boats operating around the British Isles and penetrating into the Irish Sea. Their entry into the Irish Sea, where six ships were sunk, caused the immediate abandonment of that area as an anti-submarine training ground. On 13 Jan 1945, CinC Western Approaches sent the Admiralty a comprehensive programme of anti-submarine minelaying considered neccessary in his Command. On 15 Jan, the First Sea Lord ordered that all possible steps be taken to speed up the laying of anti-submarine minefields in the Western Approaches and other vital areas. He issued a directive for the laying of deep minefields under the convoy routes in the NW and SW Approaches and off focal points in the Irish Sea, and subsequently the laying of further fields on banks and shallow patches which might be used by U-boats to fix their positions. Orders for the operation were issued by CinC Western Approaches under the title "CH" and the fishing restrictions were amended as necessary, particularly in the Irish Sea. The operation started on 16 Jan and went on until 6 May 1945. In all, 10,043 mines were laid in the NW and SW Approaches and in the Irish Sea between Oct 1944 and May 1945, the majority of these being laid under the main shipping routes in the South West.

The Naval Staff History states that captured German U-boat records covering the period were scanty, particularly after mid-Jan 1945. From those available, it appeared that between 18 Nov 1944 and the end of the war, 21 sorties were made to the Western Approaches by 20 U-boats. Of these, never more than four (and that for one week only) operated simultaneously. Between Jan and mid-Mar usually only two, sometimes three and sometimes only one were operating in these waters. From mid-Mar to the end there was never more than one U-boat present and, out of these 52 days, 15 probably saw no U-boat in the are. Obviously, these estimates now appear to be on the low side and the minefields were much more effective than believed at the time. The only known mine casualties in the area were U-260 on 12 Mar 1945 in position 51 15N, 09 15W off Galley Head (Minefield "CF(A)"), and U-1169 on 5 Apr 1945 in position 52 03N, 05 53W to the south-east of Tuskar Rock (Minefield "CH(N)").

By the end of the war, a total of 30,154 mines had been laid in the Western Approaches.

Best wishes,

Rob Hoole
RN Minewarfare & Clearance Diving Officers' Association
www.mcdoa.org.uk