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 IV
ASSAULT AREA: SCREEN AND ESCORTS

A. Allied Naval Dispositions.

27. ANCXF assigned to the appropriate Task Force Commander the task of screening the assault area against enemy naval penetration.¹ Enemy naval forces within the Channel consisted of an indeterminate number of human torpedoes, self-exploding pilotless surface craft, sea mines to be laid by aircraft, and the 195 miscellaneous vessels in the preceding section.

28. To repel these enemy forces, the Task Force Commanders established an area screen, detailing to it, a proportion of the vessels allotted them by ANCXF. Manning the area screen required a careful phasing in the use of vessels. Until allied forces arrived in the assault area, there was no screen. On arrival, a proportion of the escorts and patrol vessels took up screening patrols. Still later, other vessels, which had completed their initial tasks of boat control, close fire support, or some other job, took over patrol duties, while a proportion of the escorts returned to the U.K. in company with the convoys. In due course, most vessels capable of escort duty, were transferred to CinC Portsmouth for escort duty to facilitate his task of operating the post assault build-up convoy program.²

B. Eastern Task Force.

29. Naval Commander Eastern Task Force delegated control of naval forces screening his area to an authority known as "Captain (Patrols)"¹ During the assault phase, this authority was stationed in the ETF flagship. Later he exercised control from R.N. headquarters on the Far Shore. In both cases, he was provided with full details of the position and movement of all objects in the channel, from the radar facilities of C in C Portsmouth, NCWTF and his own ship and shore radar.

30. The system of defense employed in the eastern area was the following:
    1. constant patrols to seaward by corvettes, trawlers. and sometimes destroyers were carried out;

    2. every 24 hours one Division of four destroyers vas detailed as duty division for the entire area while two other destroyers were detailed as guard. for areas O and J. By day, these destroyers performed such other tasks as were assigned, but they were subject to call in case an attack threatened. By night they were posted as directed by Captain (Patrols). In neither case did they actively patrol up and down the defense line. The plan was that Captain Patrols would vector them against enemy forces, whose presence was discovered by radar or other means;

    3. During the hours of darkness or low visibility, this defense was augmented by a line of minesweepers anchored 5 cables apart along a defense line parallel to the shore and six miles to seaward;

    4. This defense line was continued down the eastern flank by a line called the TROUT line, composed of LCG's and LCF's, anchored 1 cable apart. The duty of the minesweepers and Landing Craft on this defense line was to prevent all enemy ships and craft from entering the British Assault Area, to illuminate the outer areas when ordered and to counter attack any submarine detected;

5. Two or three divisions of MTB's were stationed, stopped but under way, to the North eastward of the N.E. portion of the defense line;

6. Two or three sub-divisions of destroyers were stationed on patrol, to the north of the western half of the area, and sometimes to the northward of the MTB's;

7. Other light forces were stationed close inside the defense line, to act as reinforcements or as "pouncers". B.Y.M.S. and M.M.S. were anchored as minespotters, originally in the approach channels, but later in the lateral swept channel established within the area;

8. These defenses were augmented by a smoke screen laid by specially fitted craft at dawn, dusk, and as required.
31. The enemy's day activity was limited to one long range torpedo attack, by torpedo boats from LE HAVRE, at 0450 on D-day. This attack caused the loss of the Norwegian destroyer Svenner. The attack was assisted by the smoke screen laid by Allied aircraft to cover the eastern flank of the assault from batteries in the Le Havre and Villerville areas. The enemy vessels, were however, engaged, and one torpedo boat was hit by Warspite with 15-in salvoes and was considered sunk.¹

32. By night the enemy's attack was more determined. On four occasions he operated torpedo boats, and on eight occasions E and R-boats, in the eastern Task Force area. On every occasion except one these forces were intercepted and forced to retire. In no case was any success obtained by enemy. The line L.C.G. and L.C.F., anchored on the eastern flank took a heavy toll of the human torpedoes which attacked in July. Two enemy torpedo boats were also damaged, five E/R boats sunk, and E/R boat probably sunk, three E/R boats badly damaged, four E/R boats damaged. E.T.F. casualties were two boats damaged with three killed and ten wounded.

C. Western Task Force.

33. Naval Commander Western Task Force delegated command and responsibility for the area screen to CTG 122.4. Commander Area Screen (Captain Saunders in the U.S.S. Frankford). The forces employed were:
    1. Destroyer Squadrons 17 and 18,¹

    2. 18 P.C.'s,

    3. 6 British Steam Gun Boats,

    4. 33 U.S. P.T.'s.

34. The system of defense employed was as follows:
    1. The W.T.F. sector was sub-divided into areas with code names (indicated on sketch); an inner screen, about the anchorages, was formed in Areas Oregon and Ohio by Force O, and in areas Kansas and Vermont by Force U; as required to defend their own forces from landward attack by pilotless explosive motor boats, human torpedoes, etc; or as required for protection against attacks by U-boats which might have pierced the outer area screen, or as required for spotting air laid mines.²

    2. Initially the picket line, composed of destroyers.³ P.C.s, and S.G.B.s, was formed along the DIXIE Line (see sketch), and connected at its eastern end with the outer defense line of the Eastern Task Force. The pickets were supported by destroyers, in pairs or in company with P.T.s and M.T.B.s; along the MASON Line there were counter-attack divisions of P.T. boats. To avoid being confused with enemy craft all P.T.s, M.T.B.s and S.G.B.s remained in assigned stations at low speed except when enemy contact developed. They were continuously plotted by radar and coached into position by designated destroyers.

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35. The first enemy attempts to enter the assault area were made by E-boats or German coastal craft, during the hours of darkness, by approaching close inshore down the Cherbourg Peninsula. These craft were picked up on radar by destroyers in the picket line at ranges of 10 to 12 thousand yards and taken under fire. The enemy always approached at low speed, sometimes stopping when illuminated, but always withdrew in the face of destroyer gunfire. The screen was never penetrated but it is probable that the enemy laid mines on these sorties.

36. On the night of D plus 3, enemy craft endeavoured to pierce the screen from approach positions north of the DIXIE Line. These attempts were repulsed. Subsequently, in order to cut off E-Boats which were passing near Pointe de Barfleur, two attack units of S.G.B.s and P.T.s were stationed in MOUNTAIN AREA and were vectored into positions for counter attack by destroyer radar. Although these units made no known kills of enemy E-Boats, their presence and aggressive attitude are considered partly responsible for the fact that no serious threat was made against the Screen.

37. Shortly after the assault, convoys and miscellaneous ships often arrived at the assault area during darkness without previous notice. It was difficult for pickets to recognize these ships as friendly and in one instance, on 13 June, the British cable layer Murdaugh Monach was fired upon by the U.S.S. Plunkett. In addition to their screening functions the pickets assisted in reporting mines laid by aircraft, in extinguishing floating flares dropped by aircraft, and in the warning they gave of impending air attacks.

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D. Convoy Escort Forces

38. Every convoy was provided with a group of escorting vessels to protect assault and build-up forces from enemy air attacks and such enemy naval vessels as may have penetrated through the layers of defense above described. The principal problem was that of phasing the allocation of escorts so that the ships involved could be used for other tasks as well. Assault convoys were to be escorted mainly by vessels, which would perform bombardment, area screening, boat control and other duties, when they reached the assault area. A few escort groups were "loaned" to the assault forces by the C's in C, Home Commands. These, together with bombarding ships which had spent their ammunition, were used to escort early convoys returning from the assault area. The "loaned" escort groups were then "returned" to the Home Commands and applied to the build-up escort program.

39. A proportion of the escort vessels, initially assigned the assault forces for the assault phase were later transferred to C in C Portsmouth for the Build-Up phase.¹ In addition to vessels engaged in escort work during the assault, some 50 escort groups, with an average of six vessels per group, were engaged in the escort of build-up convoys. These escorts were of miscellaneous types, including escort destroyers, corvettes, motor launches and others. They were required to escort some 32 convoys and groups per day, which was the average number at sea throughout the Build-up.²

40. During the assault, command of escorts were exercised by the appropriate task force, assault force and group commanders. During the Build-up it was exercised by the Home Command through whose waters the convoy was passing. Each escort group was assigned a base port, and authorities responsible for north-bound sailings, assured, so far as possible, that escorts were assigned to north-bound convoys which were proceeding to their home ports. The convoys suffered no losses from enemy action during the assault phase.

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Footnotes:

p.425 #1 See ON 9, Para. 21, 27, 28 and 29. It will be recalled that ANCXF held naval command over the entire Channel area during the assault. Within the assault area, which was all the water south of 49° 40' N. latitude lying between the Cherbourg Peninsula and Cap Antifer, he exercised command through the Task Force Commanders. In all the rest of the channel, he exercised command through the C's inC, Home Commands, whom he directed to function generally in accordance with their normal procedure. This accounts for the fact that the Home Commands operated the patrols screening the convoy routes, while the Task Force Commanders operated the patrols screening the assault area.

p.425 #2 Details of the manner in which ANCXF arranged for the necessary transference of vessels after the assault while leaving the Task Force Commanders a free hand in continuing the area screen for their own area will be found in ON 9 and more especially on ON I, Appendix 11, sections A and B.

p.426 #1 The elaborate orders which NCETF promulgated for the defense of the British Assault Area, are contained in his British Assault Area Defense Orders (short title BAADO) dated 30 April 1944 and numbered ETF 859/4. The resume given here is very broad.

p.427 #1 According to the account of the German Naval CinC West, Admiral Krancke, the attack was carried out by the 5th German Torpedo Boat Flotilla, 15 torpedoes in all being fired. Only minor damage was sustained by the Torpedo boats; but the 15th Patrol Flotilla, stationed off Le Havre "ran into heavy enemy fire" under which one vessel sank, after striking a mine.

p.428 #1 Destroyers were employed in screening and bombarding duties in rotation.

p.428 #2 C.T.F.122 Op. Plan 2 - 44.

p.428 #3 Guard destroyers were assigned as convenient from reserve fire support destroyers of the assault forces.

p.432 #1 For allocations of escorts see ON 1 Appendix II, Section A and B, ON 13 Appendix III. For instructions to Task and Assault Force Commanders as to transferring escorts to post assault duties see ON 9, Para.16.

p.432 #2 See ON 13, Appx.III.