The South Wales Ports at War 1939-41 ] The mine war in the Bristol Channel 1939-41 ] [ A background to U-boat operations in the Bristol Channel ] Types of U-boat ] U-boats that entered the Bristol Channel ] The U-boats move to the Atlantic ] The extension of U-boat operations 1939-40 ]

A background to U-boat operations in the Bristol Channel







'the Bristol Channel was opened up to unrestricted torpedo warfare by 12 January 1940'












Above: An extract from the map which illustrates the gradual extension of the U-boat operational areas.

The Initial Situation

The U-boats started the War with a strict adherence to international law. Although the law was complicated, the ‘Prize Regulations’ were considered appropriate for U-boat operations. Merchant ships could only be sunk after being stopped and searched and steps taken to ensure the safety of the crews. Once the ships had been evacuated they could be sunk by torpedo or gunfire. It was obvious that careful observance of these rules would be impractical, and even dangerous for the U-boats so the following details were added to the order:

‘As long as war against merchant shipping is governed by the Prize Regulations, attacks are to be aimed at ships which by the protocol may be sunk without warning. These are:

  • troopships, i.e. vessels which are observed to be carrying troops or war material, or which may be identified in other ways;

  • vessels escorted by enemy ships or aircraft;

vessels taking part in enemy actions or acting in direct support of enemy operations, for example by passing intelligence. Participation in operations is presumed if a merchant ship prepares to resist or takes any action calculated to jeopardise the U-boat.

The observance of the Prize Regulations would only be obligatory if the enemy ships were unarmed.’

The reason behind this somewhat restrained approach was due to the diplomatic efforts being made to remove France from the alliance of powers against Germany. The German government was making a considerable effort to avoid any hostile action towards the French. These restrictions proved extremely difficult for the U-boats to operate effectively, particularly when using torpedoes.Where possible, early U-boat commanders would surface and use their deck gun thus giving themselves a chance to check the situation before commencing hostile action.

Convoys were frequently escorted by a mixture of British and French warships making a nonsense of the approach. The eventual solution was a series of staged orders extending the scale of operations as political relations deteriorated. Unrestricted U-boat warfare was gradually imposed by these orders. The Bristol Channel was given a special mention, due in part to the increased use of the west coast ports. U-boat command were aware that the Channel would be a focus of shipping activity as convoys assembled for routing to North America. Consequently the Bristol Channel was opened up to unrestricted torpedo warfare by 12 January 1940. The progressive removal of restrictions is shown in the following orders:


‘... ‘... all ships in the North Sea between 51 and 56 north and 4 west and 0 may be attacked without warning. Endeavour is to be made to remain unobserved during attacks in order that the enemy may suspect mines.

For political reasons an exemption was ordered on 11 January for bona fide American ships and friendly neutrals (Japanese, Spanish, Italian and Russian) and on 2 February the Danish "Maltese Cross" ships, which seem to have been forgotten, were added to the exemption.

Within a month three further announcements were made -

(ZONE B) (ZONE B) Coloured yellow 12th January 1940

. . . . All ships excepting friendly neutrals, in and to the west of the Bristol Channel may be attacked without warning."


(ZONE C) (ZONE C) 24 January 1940

. . . The area off the south-east coast from Flamborough Head to Dover, and eastwards a little beyond the British danger area is unrestricted."


(EXTENSION OF A and B) (EXTENSION OF A and B) 24 January 1940

"Area A is extended to 2 E., Area B southwards and south-west to 10 30’ west and to include the whole of the Irish Sea. Irish territorial waters extend for 10 miles."


(ZONE D) (ZONE D) 9th February, 1940

. . . . . . Area between zones A and C is now unrestricted."

The outbreak of war with Holland and Belgium changed the situation in the southern North Sea as follows:

10 May, 1940

. . . Area C is extended eastwards to the Dutch coast at Texel, and southwards and westwards to include the whole of the Channel."

To intensify action against Britain and France, U-boats were permitted on 24 May to operate unrestrictedly in the area west of Scotland (Zone E) and the area off the French Atlantic coast (Zone F).

This last measure completed the ring round Britain. Within a strip of some 60 to 100 miles around Britain and off the French Atlantic coast all ships, apart from the exceptions already given, were attacked without warning. Outside this area operations against neutral ships were still conducted in accordance with the Prize Regulations.

As there were only 18 U-boats available for operations at the beginning of the War, there was considerable thought on how they should be deployed. The initial response was to send boats out singly into inshore waters and areas where merchantmen had to cross (i.e. the North Channel, St George’s Channel, and the English Channel). U-boat command anticipated that the Royal Navy would quickly adopt the convoy system which was expected to cause much disruption to normal trade patterns. Moreover, the Prize Regulations would expose U-boats to unnecessary risk from British anti-submarine measures, at a time when the British strength in this area was still largely untested.

There were enough doubts about the military and political situation in September 1939 to prompt U-boat command to adopt a cautionary approach. The 18 boats were deployed mainly to the south-west of Ireland across the traditional shipping routes from America and the Mediterranean. The entrance to the Bristol Channel was guarded by U 28. Within days, U 28 had scored its first success, the sinking of the MV Vancouver City south of Waterford Harbour. A number of the U-boats in this first disposition sank merchant ships that were travelling without escort and in accordance with the Prize Regulations. U-boat command expected ships to be gathered into the convoy system by October with the likely outcome that U-boats were likely to come into contact with British anti-submarine forces very quickly.

Admiral Dönitz knew that the Royal Navy was placing considerable faith in its ASDIC system (a supersonic underwater reflected beam giving range and bearing). Such was British faith in this technology that senior government advisors even believed that it had largely negated the U-boat as an effective weapon! Dönitz’s aggressive U-boat commanders were keen to meet this challenge as soon as possible.

The U-boats move to the Atlantic takes the story further



The View for Sunday October 15 2000

If you want to navigate the site come to the Home Page  © Swansea History Web 2000

Up ] The South Wales Ports at War 1939-41 ] The mine war in the Bristol Channel 1939-41 ] [ A background to U-boat operations in the Bristol Channel ] Types of U-boat ] U-boats that entered the Bristol Channel ]

The History Web Bookshop    Search the Site  Contact us   The Swansea History Web CD ROM