9 September 1941 Part 2

9 September 1941 Tactical plan for permanent fortification of the Channel Islands

Higher Command submitted six specialist reports: the Inspector of Western Land Fortifications; 319th Infantry Division on Guernsey and Jersey; 83rd Infantry Division on Alderney; the Naval Commander Channel Coast; Air District Command Western France; and Anti-Aircraft Brigade VII. Rather than merge them mechanically, the corps stated its own conclusions where the specialist proposals differed. Air-force matters were left to the reports of the air district command and anti-aircraft brigade.

Military importance and likely forms of attack

The British Channel Islands protected the western coast of the Normandy peninsula and contributed to control of the Gulf of Saint-Malo, although their influence on the western entrance to the Channel was limited. Their possession and development had value only while the adjacent mainland coast remained in German hands. Alderney and Jersey lay within range of long-range mainland artillery, and all three main islands within the effective reach of land-based aircraft. Without possession of the French coast, secure supply over a long sea route would require undisputed command of the sea. Jersey and Guernsey offered only limited value as offensive naval or air bases because of their coasts, harbours, small area and terrain.

A seaborne assault would be seriously complicated by strong tidal streams, changing wind and tide, and numerous offshore and submerged rocks. Large-scale landings would be possible only when favourable tides and weather coincided. Long-range batteries on the islands and mainland were expected to make movement by major enemy warships between the islands and coast highly dangerous. Likely naval assault areas were identified as northern Alderney; the north, west and south-west of Guernsey; and western Jersey. Guernsey was regarded as the more exposed island. The corps rejected the suggestion that Jersey’s permanent fortification could be omitted.

Alderney offered comparatively favourable ground for parachute landings. Guernsey and Jersey were less suitable because of terrain, vegetation and buildings, while their restricted airfields made transport-aircraft landings difficult. An attack would probably combine all available means: strong air forces, heavy warships, modern landing craft, amphibious tanks, poor visibility and artificial smoke.

Permanent fortification

The corps approved mutually supporting coastal strongpoints intended to destroy the enemy at the landing beaches. Rocky ends of bays and, where suitable, offshore rocky islets connected at low tide were to be incorporated. Exposed strongpoints required extensive protection against artillery and air attack. Flanking positions were to be protected from the rear by their own machine guns, obstacles and fire from higher positions inland. Simpler reinforced field positions called “beach guards” were to cover gaps between the main flanking strongpoints.

Behind the coastal strongpoints, non-continuous second lines were planned on the slopes and heights rising from the flatter coasts of Guernsey and Jersey. Sector reserves, command posts, heavy weapons, observation and direction-finding posts and battery positions were to form all-round strongpoints. A third line was to seal the high south-eastern part of Guernsey and the most threatened western part of Jersey. Permanent works were required for observation and direction-finding positions, command posts, reserves, communications centres and supply installations; machine-gun positions could use reinforced permanent-field construction. Initially the third line would consist chiefly of obstacles. Alderney’s smaller works were to follow the same principles at an appropriate scale.

Artillery and anti-aircraft defence

Coastal artillery was to engage enemy warships, including the heaviest types, destroy landing craft before they reached the shore and protect harbour entrances. The proposed programme called for one four-gun 38 cm battery on each of Alderney, Guernsey and Jersey. It also called for four-gun 15 cm batteries: two on Alderney, four on Guernsey, four on Jersey and three on the western Normandy coast, with possible additional batteries for Sark and the Chausey Islands. A four-gun 12.7 cm barrage battery was required for each of Saint Peter Port and Saint Helier.

Artillery within the strongpoints would cover the zone between the minimum range of the coast-defence batteries and the shoreline. At places vulnerable to massed armoured landing vehicles, rapidly firing special guns were required farther inland. One mobile artillery battalion on each of Guernsey and Jersey was considered sufficient; the corps preferred field-howitzer batteries and rejected an excessive mixture of one field-howitzer and two mortar batteries. The proposals of Anti-Aircraft Brigade VII were accepted, with anti-aircraft artillery also serving as a major supplement to the ground-artillery system.

Ground forces

Guernsey and Jersey were each to be divided into three defensive sectors, each held by one battalion. These battalions would control every strongpoint in their sector and provide the necessary local reserves. Their final composition depended on the number and extent of the permanent works; three companies were considered appropriate, and excessive specialisation was rejected in the light of French experience on the Maginot Line. Each island was also to have a reinforced battalion as counter-attack reserve. Alderney required the proposed strongpoint crews and a reinforced-company reserve.

One anti-tank company was required on each of Guernsey and Jersey, and one platoon on Alderney. Medium armour was regarded as adequate for protecting airfields and supporting counter-attacks; speed and manoeuvrability were especially important on the narrow island roads bounded by walls, hedges and fences. Engineer strength was fixed at one company on each larger island and one platoon on Alderney, in addition to the required construction troops, depots and workshops.

Communications, reconnaissance and supply

Reconnaissance by the fortress signals staff was incomplete because of its late arrival. Mainland-to-island and inter-island cables urgently required improvement and duplication by radio-telephone. Alderney had no cable connection; at minimum it needed a reliable radio-telephone link immediately and later a cable to the mainland. The islands themselves required deeply buried, multi-pair fortress cable networks, including dedicated circuits for artillery long-base survey firing.

The defence required every available reconnaissance means. In addition to listening, direction-finding and similar equipment, air-force and naval reconnaissance units were considered indispensable. Sea and air harbours were to be expanded accordingly.

Granville and Saint-Malo, and Cherbourg for Alderney, had adequate basic port facilities if sufficient suitable shipping was available, but loading facilities at Granville and the island ports required improvement. The ports and transport vessels required air protection. Because temporary isolation had to be expected, heavy infantry weapons were to receive six daily ammunition allocations instead of four. Food reserves were to rise from forty-five to sixty days. The civil population, estimated at 65,000, also had to be included because evacuation was considered impracticable. Reliable electricity generation was essential and the necessary diesel fuel had to be stocked.

Command

As permanent construction progressed, field-army formations were to be replaced by static units. Each island needed a dedicated commander and staff. A higher commander might control all islands and the supply staffs at the mainland ports in peacetime, but during combat each island would probably be isolated. Guernsey and Jersey each required an island commander of brigade-command rank; Alderney required a battalion-command rank. The report concluded by endorsing the inspector’s separate engineering proposals and requests.

Signed von Viebahn; certified for accuracy by the corps operations section.

T-314 Roll 1603, T314_Roll_1603_English_Translation.docx. Source PDF pages 0124–0135 | Higher Command XXXXIII Army Corps, Section Ia No. 569/41 Secret Command Matter, 9 September 1941