Source: Historical Section, COMNAVEU. "Administrative History of U.S. Naval Forces in Europe, 1940-1946." vol. 5. (London, 1946): 301-337 [This manuscript, identified as United States Naval Administrative History of World War II #147-E, is located in the Navy Department Library's Rare Book Room.]

PART VI
AIR COVER FORCES FOR NEPTUNE

A. Plans for Sweeping German Minefields

71. Aircraft operated by Coastal Command, R.A.F. effectively assisted in the tasks of defending NEPTUNE. from enemy naval counter action. The tasks of these Coastal Coastal Command aircraft were:
    1. in conjunction with covering naval forces, to impede the movement of enemy warships, especially U-boats, from their northern bases to the Biscay area;

    2. in conjunction with naval covering forces, to prevent enemy vessels, and especially enemy U-boats, from penetrating into the English channel;

    3. to assist Allied naval forces in protecting NEPTUNE shipping, convoys, and assault area, from attack by enemy surface vessels and U-boats operating within the channel;

    4. to assist naval forces in disrupting enemy sea-borne transport in order to impede the movement of enemy reinforcements and supply into the assault area and in order to make German coastal supply lines difficult and costly.

72. Operational command of coastal Air Forces, operating in support of NEPTUNE, was exercised by the R.N.C.'s Home Commands in conformity with the standard British system

for control of R.A.F. anti-U-boat forces.¹ During the early stages of NEPTUNE planning, no special command channels were established for coordinating the operations of Coastal Command with operations. ANCXF reported his requirements to Admiralty or to the appropriate Home Commands, and relied on them to make the necessary arrangements. This method however proved to be clumsy, especially in connection with tasks in close support of the operation, and was found to be inadequate in providing the required degree of integration. At a later date, Admiralty authorized direct communication between Coastal Command and the various commands of the Naval Expeditionary Force. While this greatly facilitated the making of individual and specific arrangements, no integrated NEPTUNE plan for Coastal Command was developed and operations were executed by more or less improvised methods.²

73. The forces engaged in these operations included the U.K. based Aircraft and Coastal Command, six RN fleet Air Arm Squadrons, and U..S. Navy Fleet-Air-Wing Seven. To provide continuous air patrols in the South Western approaches, number 19 Group, which included the greater part of RN and USN formations of anti-U-boat aircraft, was disposed in the south and southwest under the orders of the C's-in-C, Plymouth and Western Approaches. Some anti-shipping aircraft were made available in this group, in case the enemy attempted to send surface vessels from the Bay of Biscay into the Channel. In the east and southeast Number 16 Group operated a formidable force of anti-shipping aircraft. Arrangements were made to transfer anti-U-boat squadrons from l9 Group to 16 Group of the enemy sought to operate U-boats in the southern North Sea. Number 18 Group was stationed in the north to counter any movement from northern enemy ports into the Biscay or channel area. A flexible system, of re-inforcing any of these Coastal Command Groups from the resources of the others, was devised to meet any developments which might arise.

74. Coastal Command operations in support of NEPTUNE opened in Norwegian waters on May 16. It had been anticipated that the enemy might try to reinforce his Biscay Flotillas by sending U-boats from the Baltic and Norwegian ports to the Atlantic via the Northern Transit Area. This appreciation proved correct, and to counter these movements, Number 18 Group opened a vigorous and sustained offensive. By the eve of the invasion, this offensive had resulted in 22 sightings, 13 attacks and 6 kills. By 30 June the score was 44 sightings, 28 attacks and 13 probable kills.

75. By the 6th of June, the majority of the enemy's U-boats were assembled in the Biscay area,¹ as part of his basic strategic plan, assigning the U-boat a major role in the plan to frustrate the invasion. Their task was to enter the channel and, by getting between the assaulting forces and their British Bases, to prevent the Build-Up. When the Normandy landings began the U-boats made for the assault area, proceeding on the surface whenever possible in a order to attain the utmost speed.

76. Coastal Commands main task was to prevent these U-boats from arriving inside the channel. It planned an air barrier over CORK the entire area of the western approaches to the channel, extending from the shores of Devon and Cornwall to the shores of Brittany, and from the Scilly Isles to the Cherbourg Peninsula. This area was covered with air patrols, which were so timed that every spot in CORK came under observation every thirty minutes.¹ As CORK was so wide that U-boats could not pass through it without surfacing, and as the entire surface was under constant surveillance, few, if any, submarines were able to enter the channel undetected. The solid wall of air patrols in the CORK proved effective. On the night of 6/7 June, 11 U-boats were sighted and 6 attacked; in the following 24 hours, 10 more were sighted, 6 attacked, and 3 probably sunk. After thirty days, the score for the operations in the Biscay and Channel areas was 96 U-boats sighted, 59 attacked, 6 certainly sunk, and a great many more probably or possibly sunk.

77. After this initial set back, the U-boats began to try to get through by remaining submerged and by relying on "SCHNORKEL" to ventilate and charge. ² These tactics effectively restricted their speed and freedom of manoeuvre and had a most distressing effect on their crews. The few U-boats, which did succeed in penetrating the air barrier, arrived in an exhausted condition. During the first two months no losses to the invasion forces were known to have been caused by U-boats.

78. While the U-boats were being dealt with in the south-west and the north-west, Coastal Command also cooperated with the Navy in actions against enemy surface forces. It was expected that German destroyers and light craft would operate vigorously against Allied convoys. Hence, 16 and 19 groups were strengthened to assist naval forces in warding off this threat. Soon after the invasion began, the enemy tried to reinforce his surface craft in the assault areas by bringing up destroyers from the Gironde. On the 6th of June some of these vessels we attacked by aircraft south of Brest, but the damage inflicted did not prevent the enemy from making port. Two days later, four destroyers tried to round the Brest Peninsula, but were brought to action by the Royal Navy. One destroyer was sunk, one driven ashore and a third was forced back to Brest in a damaged condition. The beached destroyer was later attacked by aircraft and reduced to a total loss. After this the enemy made no further attempts to reinforce his surface craft from the west.

79. In the early stages of the invasion, the enemy operated channel based light forces, mainly E-boats, on a considerable scale against the assault area. Some 30 of these vessels were based between Boulogne and Cherbourg, but the number was substantially reduced by surface action, including coastal aircraft, and by several heavy bombing attacks against Le Havre and Boulogne. The operations of Coastal Command against these light forces consisted mainly of continuous anti-shipping patrols in the Channel. A great many air attacks, mostly at night, were made in conjunction with naval patrols against E-boats, R-boats, minesweepers, and trawlers. In addition, aircraft carried out considerable reconnaissance work, dropping flares and directing naval forces to their targets.

80. Coastal Command also contributed to the successful Allied effort to disrupt the enemy's coastwise transport. On 15 June, north of Schiermonnikoog, a merchantman of 8,000 tons and a naval auxiliary of 4,000 tons were sunk and three minesweepers of the escort damaged. On 29 June a 1,000 ton tanker and one of its escorting minesweepers was attacked and damaged; on 20 June two "M" class minesweepers, one armed trawler, and an auxiliary were badly hit off Concarneau. Apart from the losses suffered, the enemy was obliged to divert, to purely defensive tasks, numbers of minesweepers and naval escort craft urgently required elsewhere.

81. Bomber missions also contributed to the protection of seaborne NEPTUNE forces from enemy naval action.¹ The employment of bombers in mine-laying has been described already.² On the evening of 14 June, 353 heavy bombers attacked Le Havre with 106 tons of bombs, including twenty-two 6-tonners, destroying, among other things, over 25 enemy naval vessels. On the 15th June, 297 heavy bombers attacked Boulogne, concentrating on U-boat pens.³

B. Air Defense by Combined Allied Air Forces

82. The defense of NEPTUNE from enemy air attack was a major task. Some 1,515 enemy aircraft were available for use against NEPTUNE, including 340 heavy bombers, 75 reconnaissance bombers, 75 fighter-bombers, 560 twin-engine fighters, 390 single-engine fighters, and 75 coastal aircraft. These planes were so disposed that some 185 aircraft were in the Normandy area, 360 in the Pas de Calais area, 135 in Holland, 375 in north-western Germany, and 100 in Scandinavia. The Germans were not considered to be able to deploy more than this against NEPTUNE, as their remaining air resources were required on their eastern and southern fronts.

83. Allied air forces, available for defense against hostile aircraft, consisted of the 9th U.S. Air Force, and the British Second Tactical Air Force. Taken together these comprised some 2,300 aircraft.¹ Allied fighter cover was employed in the following manner:-
    1. Five squadrons of sixteen planes each maintained a constant patrol over the convoy lanes, with five additional squadrons on call if required.

    2. Ten squadrons, of sixteen planes each maintained a constant patrol over the assault beaches, with a reserve of ten squadrons on call at all times.

    3. Some eight squadrons of light and medium bombers were available as required to bomb the enemy airfields from which attacks were launched.

84. Until air fields could be constructed on the Far Shore, the problem of maintaining fighter patrols over beaches and convoy lanes taxed the endurance of fighter craft. The distance to and from airfields in England was so great, that each plane was able to patrol for only 20 minutes over the beaches. A large proportion of the air cover effort was thus absorbed in simply going and coming.

85. The command and control of NEPTUNE air forces was not delegated to the lower echelons of command, as was the policy with Army and Naval forces. It remained, on the contrary, in the hands of the very highest echelon, AEAF. The air operation was in fact one continuos battle and not a series of local engagements. In order to keep all Allied air defense resources available to meet any enemy threat, air forces could not be tied down to a series of local tasks, but had to be free to move about over the entire area, as the enemy reaction required.

86. The single authority, exercising control over all NEPTUNE fighter defense aircraft, the "Advanced Headquarters AEAF", was located at Uxbridge, near London. This "Advanced Headquarters" was kept informed of the movements of enemy aircraft in the entire Western European area, by reconnaissance, radar, and other resources. All such information was fed into Uxbridge and air deployments were made accordingly.

The fields from which the aircraft operated were scattered all over southern England. This system of remote control was obviously unable to direct effectively local movements of aircraft in the assault area. This was assured from three fighter direction tenders. These were naval landing ships (LST's) equipped with all the radio and radar gear required for the tactical control of aircraft. An elaborate operations room was installed in which the movements of all aircraft, friendly or hostile was plotted. Intelligence of the local situation was provided by local radar and reconnaissance. Intelligence of more distant air movements was supplied by radio from Uxbridge. The navy operated the vessels, while airforce commands operated the fighter control.
86. Under this system of local control, planes on patrol, and also reserve planes sent specially as reinforcements, were despatched by the control authority at Uxbridge. On arrival each plane made radio contact with the air operation room of the fighter direction tender. While the plane remained in the area, the FDT vectored it to its target, and generally directed its movements. When its tour was completed, usually because its gasoline was exhausted, control of the plane was returned to Uxbridge. Three FDT were employed for the operation, one stationed in the WTF area, one in the ETF area, and one in mid-channel. Fighter Direction Operation rooms complete with radar and radio equipment were installed on three other ships, which were stand-bys in case the FDT's were sunk.

87. The Air Force Command intended to transfer local control of fighter aircraft from the FDT's to the French Shore on D plus 1. To do so they landed several Ground Control Intercept (GCI) parties on D-day. These were, however, badly mauled in landing and were unable to function until after D plus 6. In order to enable individual ships to call for help against hostile aircraft, and to provide for relaying information of movements of hostile aircraft, a special radio channel was provided. Calls for help were received at Uxbridge and on the FDT's, one or the other of which took appropriate action. The Joint Force Broadcast a general purpose radio circuit, to which nearly every vessel was tuned, was used for air warnings, to keep ships and craft warned of movements of hostile and friendly planes.

87. The anti-aircraft armament of all vessels was available for use against hostile aircraft, while each Commanding Officer was responsible for using it for the protection of his own ship. The main problem, however, was that of keeping ships from shooting down friendly aircraft, and of coordinating the use of anti-aircraft guns with movements of air covering forces. In order to drive enemy planes by anti-aircraft fire up to an altitude where the Allied fighters could deal with them, and then to stop AA fire, so that these friendly planes could do their job, a plan was tried which provided that ships should fire their AA only on a signal, and should cease fire on a signal. This plan however, did not work, as the gunners on many ships did not obey the signals. At a later date, the plan was tried again in captured ports with some success.

88. The enemy's air reaction to NEPTUNE was unexpectedly small. Most of his fighters were used in a defensive role against Allied bombers. The first sortie against NEPTUNE shipping came at about 3 o'clock on D-day, some fifteen hours after the first arrival in the assault area. During the following night some eight-five aircraft, mostly mine layers, flew over the beaches and shipping lanes. On D plus 1, some fifty-nine enemy aircraft were in the battle area of which fifteen were destroyed. Thereafter the enemy's reaction dwindled gradually. By the middle of July, air attacks on the NEPTUNE area had virtually ceased.

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p.450 #1 This system was broadly as follows: (a) Coastal Command, whose primary mission was anti-U-boat warfare, was one of the major sub-divisions of the R.A.F., (some other major sub-divisions were Bomber Command, Training Command, Fighter Command, etc.) and was commanded by the Air Chief Marshal, Commander in Chief Coastal Command. For administrative and logistic purposes he was directly under the command of British Chief of Air Staff, but the Chief of Air Staff had assigned operational control of Coastal Command Forces to Admiralty.
(b) The major operational sub-divisions of Coastal Command were GROUPS. Admiralty assigned operational control of groups based in the United Kingdom to appropriate Home Commands.
(c) The C's in C, Home Command, employing a suitable air staff from Coastal Command, and in conjunction with naval forces, then operated assigned groups for air patrol of the waters for which they were responsible.
(d) Supervision and coordination of joint operations was effected by the joint control of Admiralty and C in C Coastal Command. (See Fairwing 7, History, for further details.)

p.450 #2 ANCXF Report Vol. l, Page 30.

p.451 #1 On that date they (the U-boats) were offensively deployed. This fact is another striking indication of the fact that the enemy had been unable to discover the approximate invasion date.

p.452 #1 The reason the thirty minute interval was chosen was because a U-boat was believed to use up, in a crash dive approximately as much battery energy as could be charged. into the batteries in thirty minutes surface charging.

p.452 #2 The "SCHNORKEL" was a pipe with two vents which was pushed. up from the submarines interior. This enabled a U-boat, at periscope depth, to expel exhaust gases from its diesel motors and suck in fresh air from above the surface. Submarines employing Schnorkel were hard to detect because the exposed portions were only some 20 inches in diameter and extended only some 6 feet above the water. During the early months of the invasion the enemy had not fully learned how to use it, but later in the summer when they were able to use it at greater depth and with less exposure above the surface, the entire character of the anti-U-boat effort was changed.

p.454 #1 Questions relating to the integration of Naval and Bomber operations are dealt with in Chapter VIII which deals generally with Bombardment and Air Bombing in their role of defense against enemy shore action and offensive assistance to the army.

p.454 #2 See Section 2, of this Chapter.

p.454 #3 These were berths for U-boats covered over by reinforced concrete.

p.455 #1 This figure does not include Allied Bomber Forces, nor does it include fighters employed in the support of Bombers. Bombers, however, contributed effectively to the defense of NEPTUNE against enemy hostile aircraft by executing several attacks on enemy airfields from which hostile aircraft were flown.