844                                                19 JUL 1944

From:    	Commander Task Force ONE TWO TWO.
To  :		Commander-in-Chief, United States Fleet.

Via :		Commander, U.S. Naval Forces, Europe.
Subject:	Naval Combat Demolition Units; report of.

Reference:	(a) CominCh ltr. FF1/98-2 serial; 001192 of
		     16 April, 1944.

Enclosure:	(A) Lt.(Jg) H.L. BLACKWELL, Jr., D-V(G), USNR,
		     ltr. A16-3 of 15 July, 1944 with attached

    1.	        Enclosure (A) is forwarded in accordance with
reference (a).

					A.D. STRUBLE,
					Chief Of Staff.

File No.
CTF122    /A16-3 
                          UNITED STATES FLEET
                       TASK FORCE ONE TWO TWO

                                                               Navy 803
                                                               Care Fleet Post Office
                                                               New York, N. Y.

                                              15 July, 1944.

From:        Lt. (jg) H.L. BLACKWELL, Jr. D-V(G) USNR.
To  :        Commander Task Force ONE TWO TWO.

Subject:     Naval Combat Demolition units; report of.

Reference:   (a) ComNavEu Orders to Lt.(jg) Blackwell
                  P16-3/00 of 3 Tune, 1944 and endorsements

Enclosure:   (1) Report on the work of the U.S. Naval Combat
                  Demolition units in operation NEPTUNE.

    1.       This officer has been on temporary duty with
Task Force ONE TWO TWO for the purpose of collecting information
on the work of the U.S. Naval Combat Demolition Units in
breaching beach obstacles.

    2.       Some of the material collected has been briefed
to make up the report which forms Enclosure (1) of this letter.

                                         Respectfully submitted,
                                         H.L. BLACKWELL, JR.
                                         Lt. (jg), USNR.

                               REPORT ON
                         OPERATION "NEPTUNE"
                              as part of
                             TASK FORCE 122

Submitted by:
Lt.(jg) H. L. BlackWell, Jr. D-V(G) , USNR.
5 July, 1944.

TABLE OF CONTENTS Section I - Chronological sketch of NCDUs in U.K. November 1943 -- Tune 6, 1944 . . . . . . pp. 1-8 Section II - The Operation. A. Brief Summary. B. Force OMAHA. C. Force UTAH . . . . . . . . . . . . . . pp. 9-19 Section III - Recommendations for Future Operations. A. General, for NCDU work under any circumstances. B. Recommendations Specifically for Operations similar to NEPTUNE . . . . . . . . . . . . . . pp. 20-25 Enclosures : (1) Tabular summary of Gap Clearance, D-day, Force '0'. (2) OMAHA Beach Map, with trace to show D-day Gap Clearance. (3) Tabular summary of Gap Clearance, D-day, Force 'U'. (4) UTAH Beach Map, with trace to show D-day Gap Clearance. (5) Table of Methods used (Obstacle, Charge employed, Results). (6) Demolition Operation Order, Force '0'. (7) Demoliton Operation Order, Force 'U'.
SECTION ONE CHRONOLOGICAL SKETCH 1. Summary. The first U. S. Naval Combat Demolition Unit arrived in England on 31 October, 1943 Between then and 6 June 1944, the number of units rose to 32, training and exercises were conducted, a specialized charge developed, and the clearance of obstacles on NEPTUNE beaches was planned and prepared. A sketch of these events forms the balance of this section. 2. Sketch history 31 Oct. 1943 - NCDU #ll Arrived in U.K. ordered to Falmouth. 15 Dec. 14 - NCDUs 22 through 27 arrived. To Falmouth. 25 Dec. - NCDUs 28, 29 and 30 arrived Scotland and after 1 January, 1944, went to Falmouth. All units were then under administration of ComLanCrabEu, acting for Com11thPhib. They were also under the jurisdiction or the C.O. of their base. Within the group itself, there was a Senior Officer (Lt. Robert Smith, CEC, USNR, but no officially designated commanding ofricer. Units drew up an advanced training program for themselves, but the lack of a Unit Commander caused some difficulty in getting training under way, especially in the matter of getting obstacles constructed for the Units to demolish. Late January - Lt.(jg) Heideman ordered to Fort Pierce, Florida, for demonstration there, representing Com11thPhib. 14 Feb. 1944 - The 10 NCDUs were placed administratively under the Commander, Beach Battalions, ELEVENTH Amphibious Force. They were broken into roughly equal groups numbered I, II, and III, and these assigned to the 7th, 6th and 2nd Beach Battalions. Group Commanders appointed were: Lt.(jg) Heideman, O-V(S), USNR, I, Lt. (jg) Cooper, D-V(G), USNR, II, and Lt. Smith, CEC, USNR, III. The scope of their authority as Group Commanders was never defined, for them; and no one of them was ever officially designated Commanding Offficer of the entire group of Units, though Lt. Smith was Senior Officer. By mutual agreement, negotiations with higher commanders were conducted largely through and by Lt. Smith, despite lack of official authority which made his position difficult. Group I went to Salcombe; Group II, first to Salcombe and thence near Swansea, Wales; and Group III went to Fowey. It was then thought that NCDUs would be operating with troops of the 3rd Army Engineer Special Brigades of First Army. Joint training was undertaken; but this plan was later abandoned. 25 Feb. 1944 - First obstacles in NEPTUNE area reported this date. Report based on photo sorties flown on 20 and 21 February. From this date obstacles grew steadily denser till D-day. Late February - Between this time and mid-April, NCDUs at Fowey did considerable experimental work. Tests were run to determine best method of breaching such obstacles as wooden piling, steel wire rope, scaffolding and Element C. However, NCDUs doing this work were not informed what obstacles were being found on intended assault beaches. The Hagensen Pack charge (2 lbs. of C2 in canvas) was developed at this time, primarily for use on steel obstacles (plasticity, small production of shrapnel, ease of attachment, etc.). Obstacles for these experiments were supplied by of the 1st E.S.B. , on Pentwain (sp?) Beach. Training conducted especially against Element C ("dry runs" in which charges were fitted but not fired.) Early March - Lt.(jg) Heideman returned from USA with understandings that initial quantities of (a) Reddy Fox charges, and (b) Dunlop or substitute Underwater Swim Suits would be delivered for NCDUs in U.K. by April 1. 15 March - NCDUs 41 through 46 arrived, and were at once divided among the 3 Beach Battalions. 1 April(about)-50 Swim Suits, substitutes for the Dunlop U.W.S.S. Mk. 1 but not as good, arrived by air. Mid-April - Lt. (jg) Padgett and NCDU #127 arrived. Total number of Units now was 17, split equally among the three Groups; each unit, 1 officer and five men, usually including a chief or lst class. 15 April - The Commander, 11th Amphibious Force, in conjunction with V Corps, U. S. Army, called in the Naval Demolition Group Commanders and some other Naval Demolition Officers for advice on obstacle clearance under certain hypothetical conditions. Officers of NCDU guessed, but were never told, that the actual operational plan was being made. The Demolition Operation Orders of the two Forces were not written at till later, but at this time the following basic decisions were made: (a) that obstacles could be expected to continue growing denser until the operation; (b) that the obstacles should be attacked when in three feet of water or less; and (c) that hand placed charges were the most practicable method under the circumstances. Lt.Col. O'Neill, of the 112th Combat Engineer Battalion who had attended the Ft. Pierce Demonstration in February, was called in as an advisor, and later was made Commanding Officer of V Corps' Special Engineer Task Force. (Naval Combat Demolition Units in Force 'O' were nominally a part of this Army Task Force. In actual fact, NCDUs and Army Demolition Units operated in the closest harmony, but under their respective commands.) During all planning, NCDU officers emphasized that men setting handplaced charges could accomplish their mission only if opposing fire were neutralized. Mid-April - All NCDUs moved to Assault Training Center, Woolacombe, N. Devon, for a special advanced training program based on the intended conditions of actual operation. This training program was arranged largely by Lt. Smith, and the other NCDU Group Commanders and officers, with Major Richard Fairbairn, R.E., British Liaison Officer on the Staff of Com11thPhib. (Major Fairbairn had seen the development of U.S.N. Combat Demolition, starting at Fort Pierce, where he went in June 1943, in an advisory capacity when the NCDU training program was first being set up.) At Woolacombe, NCDUs trained with the troops of the 146th, 299th, and 237th Combat Engineer Battalions, with whom they actually worked during the operation. (ConEleventhPhib at this time loaned Lt.(jg) John Martin to the NCDUs. Lt. Martin's help in procuring, organizing, and loading gear, from this time until the operation, was a major contribution to the success of the Demolition work.) Naval Scouts joined NCDUs at the A.T.C. for a time, to do gap-marking work. This plan, however, was later abandoned, and gap-marking was made a function of the NCDUs themselves. At this time, it order to provide the Navy with additional trained demolition personnel considerered necessary, the Combat Engineer Battalions turned over five soldiers to the NCDUs. (And it is worth note that though it is often the practice, when lending men, to get rid of dead-wood, these men were generally capable, intelligent, and well-trained.) These five men remained an integral Dart or each NCD Unit till after the assault when they were gradually returned to their companies. While NCDUs were at Assault Training Center, Col. Reinhardt, C.O. of the 1278th Engineers, took an active part in obstacle work, and became especiaiiy closely associate during D-day with demolition units of Force 'U'. 23 April - Air photos this date showed the sympathetic detonation of regularly-placed small charges, caused by bomb explosion below water line. Investigation (confirmed by reconnaissance parties sent to the beaches) showed these small charges to be Tellermines, used on top of obstacles against craft. Capt. T. F. Wellings, Force Gunnery Officer of CTF 122, took charge of NCDUs; as previously pointed out, they had suffered since their arrival for lack of, a single, high-ranking Cormanding Officer. 3 May 1944 - Lt.Cdr. Joseph H. Gibbons, USN, and Lt.Cdr. Herbert A. Peterson USN, arrived by air in response to despatches sent by Com11thPhib ana CTF 122, which requested Commanding Officers for Demolition Units of the two forces. They took charge of the NCDUs, under general supervision of Capt. Wellings. 5 May 1944 - Approximately 100 Seamen 2c arrived fron Rosneath to augment NCDUs. These men had volunteered, with very vague ideas of what they were volunteering for. They were inexperienced in demolition work end therefore were apportioned evenly among the Units for training. Just before the operation, those unsuited for demolition work were turned over to Salcombe Base while two (or sometimes three) of the others were retained with each unit. Those retained, however, were given non-technical work such as tending rubber boats etc. 6 May 1944 - Units 128 and 130 through 142 arrived by air, and went direct to Assault Training Center. 15 May 1944 - All NCDUs moved into Salcombe. The time here was spent in obtaining final items of gear, and in preparing Hagensen and other charges, detonator assemblies, and and personal equipment. Mid-May - Several freighters arrived in scattered U. K. ports, carrying Reddy Foxes, Apex boat components, etc. These were stored "for future reference." 27 May - NCDUs of Force 'U' went to marshalling area near Dartmouth. Officers received partial briefing. 31 May 1 - NCDUs of Force '0' went to Portland for embarkation. Support Units were put aboard the LST Princess Maud. Assault Units went aboard LCTs. 2 June - NCDUs of Force 'U' were loaded aboard LSTs, with their LCVPs which would carry them to the beach. 2 June - All officers of NCDUs of Force 'O' were briefed aboard the USS Ancon. 3 June - Force 'U' officers further briefed. Crews briefed aboard their craft. Craft got under way, but bad weather forced postponement of the Operation. 4 June - Craft again got under way. 6 June - From about 0200 on, craft arrived off coast of France. NCDUs and Army Demolition Units embarked in their smaller craft. Boat Team #6 had made almost entire crossing in their LCM when LCT (HE) 2075 foundered; Boat Team #2 had embarked in LCM at 2300 and cast loose at 0330, when LCT(A) 2227 was crippled by flooded engine room; and Boat Team #11 had to abandon their LCT at 0200, in sinking condition. Foundering of 2075 was result of water coming in where starboard rail had been out away and replaced; replaced section swung one way only, like a valve, admitting water and then impounding it. The Assault Units of Force '0' went ashore to fulfill their mission after almost a week aboard LCTs (whose decks were often awash), having had no hot food or exercise. Support NCDUs of Force '0' were fairly fresh after crossing on LSI; and NCDUs of Force 'U' had been on LSTs. It is felt that use of LSTs, if available, is preferable. The story of the actual operation is told in Section II.

                                   SECTION II


A. Brief Summary of the Section.

    This section covers the actual assault and post-assault work
of breaching the beach obstacles in operation NEPTUNE. It presents
information on the Operation Plan, the methods used, the difficulties
encountered and the results obtained. It is divided into two sub-
sections, one devoted to each Force.

B. Force OMAHA

   1. The Mission of the NCDUs.

      (a) The. following is quoted from the Demolition Operation
Order, part of Operation order No. 1-44 of Assault Force 'O' of the
Western Naval Task Force, dated 31 May, 1944 (Encl. (6) hereof)

      1. The Naval Combat Demolition Group is associated
         and working with an Army Demolition group consisting
         of two battalions of Combat Engineers attached to the
         V Corps. One NCDU together with one Army combat demolition 
         unit forms a Gap Assault Team.
         NCD Sections TWO and ONE will form part Of Assault
         Group 0-1 and 0-2, respectively, of Force 'O' and will
         function under the Commanders of those Assault Groups.

      2. This (Demolition) Group will: (1) Clear and mark
         sixteen gaps, fifty yards wide, through the seaward band
         of obstacles on OMAHA beaches; two on F0X GREEN, six on
         EASY RED, two on EASY GREEN, two on DOG RED, two on DOG
         WHITE, and two on DOG GREEN.
         (2) Widen the gaps in the seaward band of obstacles until
         the entire band is cleared.
         (3) Assist the Special Army Engineer Demolition Group
         in clearing gaps through other bands of obstacles and
         removing all obstacles from the OMAHA beaches.
(b) In detail, this mission involved clearance of obstacles in roughly the following order from seaward to landward: i. Scattered Element C, either interspersed with ramps (ii. below) or placed in continuous linear groups; most of it the newer, smaller type, about 8' high; ii. wooden ramps, having one sloped log running from the beach level to the apex of a triangular frame or to the top of a single vertical log; logs 10-18" diameter (some larger on UTAH); height 10-12 feet; sloping member 15-18 feet long; sloping log supported by 1, 2, or 3 legs; these ramps were 20-30 feet apart, in rough bands, either with pilings or Element C; iii. single log pilings, 10-18 inches diameter (UTAH reports some almost 24"), set at 15-25 foot intervals, either in a single row or in staggered bands; iv. steel hedgehogs, each leg about 4½ feet, made of channel irons (about 4"x4") welded to central gusset plates, which were in turn bolted together; ends of channels closed with a welded triangular plate to prevent sinking into sand-clay; v. Tellermines 35, 42, and 43, on seaward face of high (usually inshore) end of ramps, or on tops of pilings (bevelled, sloping seaward so as to expose mine to horizontal pressure as well as vertical), or at top-center of Element C; the average was about 1 Tellermine to every 7th obstacle, but they were denser or less dense at many places (UTAH NCDUs encountered NO Tellermines in Assault area, but on originally-planned beaches they were present); mines had normal T. Mi. Z. igniters, were not booby-trapped; they were waterproofed with black, tarry compound very like DuPont product, and it is assumed this must have been effective as mines were still active (mining having been first noticed 23 April). Individual Tellermines were buried in the sand at many scattered points, and damaged vehicles as late as D Plus 4; but beach was swept by engineers with SCR 625 detector, and no minefield was found within the tidal range; it is therefor believed that mines within tidal range had fallen or been blown from obstacles, for they were neither dense nor regular enough to have been a deliberate field. 2. Gap Clearance. A tabular summary, and a map, showing gaps cleared in obstacles on OMAHA beaches are attached as Enclosures (1) and (2) respectively. The same material, generalized, is presented herewith in narrative form. The Assault NCDUs and Army Demolition Units (collectively called Gap Assault Teams) touched down on OMAHA beaches at 0633 - 0635, with a single exception. All were to the left of their assigned beaches, starting with Team No. 1 on DOG WHITE, 700 yards east of their intended landing on DOG GREEN. Others were as much as 1500 yards east of their assigned landings, though still within the OMAHA beaches. The error is variously attributed to haze over the shoreline, absence or failure of guiding craft, and shore currents. The type and intensity of the fire that met them is by now well known. Many Boat Teams arrived ahead of the Assault infantry, others simultaneously with them, and a few after them as planned. Two tanks and a tank dozer were assigned with each Army Demolition unit. Some of these arrived successfully and did yeoman service in drawing fire away from the Demolition personnel, and returning fire, and later (especially D-day afternoon low tide) in dozing out the obstacles. (Of the rest, some were lost with their LCTs, some were landed late in the day, and some, landed successfully, were knocked out traversing the beach from their landing-point to their assigned Gap Area). Almost all units proceeded at once to lay charges; and they were ready to fire in a maximun of 20 minutes. [Enclosure (5) presents details of charges uded, their placement, etc.] Six complete gaps, through all bands of obstacles, were blown during the assault low-tide, most of them by H plus 30 minutes. Three partial gaps, through either the seaward or the landward bands, were also blown at this time. Four additional clear gaps were made as the tide receded that afternoon, and the three partial gaps were completed; meanwhile some of the morning gaps were being widened leftwards, as planned, so that there were at least 13 gaps averaging about 70 yards each that afternoon. Of the Teams who failed to fire, at least five Army or Navy units were prevented from setting off charges which they had fitted by the presence among the obstacles of either assault or later waves of infantry, and even vehicles. (At least two units report misfires caused by the fact that the primacord linking their various charged obstacles was cut by troops and vehicles, passing through the gaps despite efforts to signal them away.) Death prevented three other Navy units from firing. (Of these, one was caught aboard the LCM by machine gun fire, while they strove to off-load their rubber boat; another was eliminated, after setting its charges, by well-placed mortar fire. The third was blown up after bringing in its rubber boat, when a direct hit set off the auxiliary explosives in it and somehow also the charges at the obstacles where men still were.) A freak accident caused the failure of another naval group; the officer was about to pull the twin friction-igniters, when a bit of shrapnel cut the two fuses and his finger as well. The enemy saved one naval team the trouble of pulling its igniters, when a bullet or fragment managed somehow to set off the primacord and all the charges! Despite the casualties, surviving units continued working, with general disregard for personal safety. A notable example of courage was given by men who voluntarily placed charges on Tellermines atop obstacles, 10 or 12 feet above the beach; in the face of accurate rifle and machine-gun fire, they climbed on each others shoulders or shinnied up the pilings and ramps. Support Teams, due on the beaches at H Plus 8 (0638), were all late by amounts varying from 20 to 60 minutes. Their LCMs had arrived late for loading at the LSI Princess Maud. Their task was made difficult by height of tide which in one case was reported above the landward obstacle (location indefinite). The plans had provided for the marking of gaps. Two white triangular range-markers on poles to be stuck in the sand would show the centerline of each gap. Its extremities, to seaward, would be marked by a pair of can buoys holding green flags. Many buoys, because of their bulk, were left in the rubber boats. Among those brought ashore, the cans of several were pierced by bullets or shrapnel, leaving either one buoy of the pair or none. At least two units put out their single remaining buoy at the edge of their gap; but they seemed to serve little purpose; some coxswains apparently thought they were merely wreck markers, without knowledge to which side they should leave them. The error that carried some teams to the extreme left of FOX RED may have been a very fortunate one. One all-Army unit and several combined A-N units blew and dozed gaps in this area on the afternoon of D-day and the morning of D-plus-1. Tanks and troops entered there, and passed inland over the unscheduled beach exit (at 697893) leading to Cabourg and Colleville. The presence of these gaps may therefore have been of incidental assistance in the capture of Colleville. By the evening of D-day, 40(?) per cent of the obstacled area on Omaha had been cleared. 85 % had been cleared by D-plus-2 days. Work of course continued, by both explosive and mechanical means, on succeeding days, and by 1200 of D-Plus-4, Lt.-Cdr. Gibbons reported that the beach was clear of all enemy obstacles that constituted a hazard to craft. The NCDUs of Force 'O' left for the U.K. on 27 June, 1944. 3. Methods used. Enclosure (5) is a table showing the amount and placement of charge for each different type of obstacle, and the results obtained, covering the work of both Forces. It refers primarily to methods of the Naval Combat Demolition Unitss but is generally applicable to Army Engineer technique also. C. Force UTAH. 1. The Mission of the NCDUs. (a) The following is quoted from the Demolition Plan, which, forms Appendix Three to Annex George of Operation Order No. 3-44, dated 15 may, 1944, (Enclosure (7) hereof). 1. At the present time it is contemplated that all obstacles will be breached above water. As above-water demolition is primarily an Army function, the Naval Demolition Units are coordinated with the Army Demolition Units, under the supervision of the Commander of the Army units. 2. The force will breach and destroy above-water obstacles on UTAH BEACHES in order to permit the unimpeded landing of personnel, vehicles, and equipment of the VII Corps, U. S. Army. 3. (a) Naval Combat Demolition Units clear four gaps 50 yards wide at 250 yard intervals through the seaward band of obstacles on each beach. Widen gaps to the left until entire band of obstacles is cleared. (b) Details of mission. Force 'U' made its entire landing 1500-odd yards south south of the intended location. This accident turned out to be very fortunate, as a glance at the Obstacle Overprint map at Enclosure (4) will show. The detailed mission of the NCDUs here involved the clearance of the following obstacles: i. scattered wooded ramps, some like those on OMAHA, others looking like a large letter 'A' the feet of which rest on the sand while the members slope upward, with the apex resting on a frame or a single leg; timbers were 10-24 inches diameter; ii. three sparse bands of wooden piling, or wooden and concrete piles mingled; wooden piles were as met on OMAHA; concrete piles were re-inforced with half-inch bars at each corner (square cross-section); pilings were irregularly spaced on about 35-foot centers; iii. Eight unconnected "bays" of Element C, scattered to seaward of other obstacles; iv. hedgehogs, of same dimensions as OMAHA, but some reported as welded throughout instead of partially bolted; these were mostly at northern end of actual assault area; in a well-defined band to landward, spaced about 15-20 feet apart; in some instances a single strand of wire was strung between each two hedgehogs, perhaps to foul screws of landing craft at high water; v. tetrahedra, made of six equal pre-formed, reinforced concrete limbs fitted so as to form four equilater triangles, capable of resting on any of them; by having a pin thrust hinge-wise through the projecting loop-ends of the reinforcing bars at each end; vi. tetrahedra, steel, standard anti-tank type; vii. tellermines were conspicuous by their absence in the actual assault area; they were fairly dense in the intended assault area. (c) In general, obstacles varied from 'moderate' on the right flank to 'negligible' on the left flank. Obstacles were denser everywhere than May 30th overprint shows, and extended further south. As on OMAHA, Element C was usually interspersed with ramps. All obstacles were on very wide centers (25-35 feet), in poorly defined bands or singly. The commonest were reinforced concrete posts and wooden pilings, in about 2-1 ratio, the tops of wooden posts generally recessed for Tellermining; concrete tetrahedra were the next commonest. (d) Lt. Smith reports the installation of fixed flamethrowers, remote-controlled, behind the beach seawall south of the exit at 452967 (La Grande Dune). Description given in Encl. (5). 2. Gap Clearance A tabular and map summary of UTAH gap clearance work, similar to that given for OMAHA in Enclosures (1) and (2), is contained in Enclosures (3) and (4). These must be read with the same reservations as were stated above for the OMAHA summary. All the UTAH NCDUs touched down within one or two minutes of their scheduled times H + 3. As is now well-known, they were all about 1500 yards south (left) of their intended assault area; and the units themselves were not in the order from right to left which had been planned, but they spaced themselves out, and allowed this fact to make no difference in their work. The fact of landing so far south of their planned areas resulted in their finding only light opposing fire, and this fact must be taken as an important factor in the success of the demolitions operations. Officers report that with few exceptions they were hardly aware of the opposing fire till they were through work and took cover. (This does not alter the fact that machinegun, artillery, and rifle fire took toll of NCDU personnel leaving 6 dead and 11 wounded. The navigational error further assisted NCDUs inasmuch as the obstacles were far lighter than where they should have landed. This is a second major factor in their success. All units at once went to work laying charges, and all blew their first gaps, generally of more then fifty yards clear through from water-line to the barbed wire-at the seawall, in 5 - 8 minutes. They immediately wired and fired their second, and many of them their third shots, widening their gaps leftward (south) as per plan. By 0800 of D-day morning, Lt.-Cdr. Peterson was able to see. that the entire beach in the assault area was clear of enemy obstacles. The comparative lightness of the opposing fire was responsible for NCDUs here not being held up by the presence of the assault infantry pinned down among the obstacles. The infantry, which in all reported cases arrived right on schedule neither behind it nor ahead it, was able to go straight across the beach and over the seawall. When the Support NCDUs arrived, about on schedule, they found in general that work was well in hand in their assigned areas, and were assigned other spots to work, including the extreme northern flank of the assault beach. The Army Engineer Demolition Teams hit the beach a little late, and when they proceeded at once to work on the breaching of seawall exits and the clearance of the minefields behind it, progress was good enough. Some Army personnel remained on the beach, however, and breached gaps edge-to-edge with Navy gaps. Cooperation was excellent. On subsequent days, large areas were cleared on the flanks of the assault beaches, and even in entirely separate areas (ROGER WHITE). All firing was electrical, preceded in each case by use of the planned warning signal, a purple smoke grenade. Shellholes provided cover. There were few misfires, but of those which did occur, one cause was the cutting of primacord by infantry and vehicles coming through the gap after the setting of the charges. Gap-marking gear was not used, since there were no gaps to mark. The plan was to use range markers, green flags, and red and black channel markers. NCDUs left UTAH beach for the U.K. on 13 June, 1944. 3. Methods used. Enclosure (5) is a table showing the amount and placement of charge for each differenct type of obstacle found on either OMAHA or UTAH. It referes primarily to the work of the NAVAL Combat Demolition Units, but is generally applicable also to Army Engineer Demolition Technique. The only major difference in practice between the two Forces is that on UTAH all firing was done electrically. The only other major difference affects the Army's work primarily: the absence of Tellermines on the obstacles in the assault area enabled dozer work to proceed without a mine-clearing party first. (Incidentally, almost all Army officers on OMAHA, felt that more dozers could have been used there; it is a question whether the same is true of UTAH in view of the lightness of the obstacles.)

                             SECTION III

Recommendations for Future Operations.

             The recommendations made in this section are based on suggestions 
made by operational NCDU officers and Army Demolition officers. In
other words, they represent the views of some of those who have actually
done this type of work, and who will be called on to do it again if there
are further operations here.

A. General recommendations, for NCDU work under any circumstances.

   1. Organization.

      The lack of a Commanding Officer of some rank meant that much
of the valuable early months spent by the first ten units in the U.K. was
wasted. This lack had three effects, stated below.
      (i) it produced a lack of direction within the group itself,
where there were ensigns, lieutenants (jg) , and one full lieutenant,
none of them officially designated as C.O.; each was officially O-in-C
of his own Unit and no more, and therefore none desired to appropriate 
control of the Group though all were aware of the need for a command.
      (ii) The group had no representative to look after its interests 
with the various interested commands. At the same time, this lack
was accentuated by the fact that there were several commands having some
jurisdiction over the units.
      (iii) Such a Commanding Officer might well have succeeded in
obtaining certain critical items of gear, such as Dunlop U.W. Swim Suits,
and Reddy Fox Charges, in time to include their use in the planning of
the operation (Swim Suits might enable an Underwater attack, Reddy Fox
might obviate hend-placed charges, etc.).

      It is therefore suggested that NCDUs, when being despatched
to a  theatre as a group, should be given a formal group organization
before leaving the U. S. A. By the time the Units of this Task Force
were ready for the operation, they had officers performing all the
following functions (whether officially designated as such or not):
Commanding Officer, Executive Officer, Supply Officer, Intelligence Officer,
and First Lieutenant; and there were men acting as yeomen, storekeepers,
mess cooks, etc; all this was either instead of or in addition to regular
duties with Naval Combat Demolition Units. By May the group was almost
400 officers and men; and their presence put a heavy demand on facilities
of Bases for transportation, feeding, clothing, general
and technical supplies, and medical attention.
      In short, a group or this size should probably become a Commissioned 

   2. Army-Navy Cooperation.
      In all the aspects of Obstacle-clearance work in Neptune with
which this observer is familiar, Army-Navy cooperation was virtually
perfect. Especially on the beach itself (notably 0MAHA) where conditions
kept the Army Teams on the beach several days), the two groups of teams
and their respective commands operated in complete harmony. The relationship 
was closest within the Navy units themselves; where five Army men
and between five and seven Navy men worked as one team, under a Naval
      The recommendation in this instance is not to change but rather
to extend such cooperation.
3. Sea Transport on operations to point where NCDUs will embark in small craft to go to beach should if possible be done in large vessels such as LSI or LST, rather than making a long trip like the channel crossing in LCT or even LCM. 4. Landing Craft, taking NCDUs to beach should, if possible, be permanently assigned to that Unit, and be trained with it. 5. Hagensen Pack is recommended for use in all future operations where obstacles at all similar to those in NEPTUNE are to be attacked with hand-placed charges. It has received universal endorsement from Naval and Army Demolition Officers. B. Recommendations specifically for Operations similar to NEPTUNE. 1. Enemy Fire. Experience in NEPTUNE bears out the statement that hand-placed charges can be used sucessfully only if enemy fire has been neutralized. It is recommended that the Demolition Units, the tanks covering them, and the Assault Infantry be considered an inseparable Team, and the plan be so made that all the components of the Team will arrive on the beach together -- even if it is the wrong beach. Corrollary recomendation is that the three elements of the team should be exercised together, and be personally acquainted, for a week or so before the operation. It is also recommended yhat Assault Infantry be allowed more time, in tne plan, to neutralize enemy fire before demolition begins. This would facilitate demolition work by (a) reducing casualties and (b) giving infantry time to get beyond bbstacles. 2. Technique of Ramming Obstacles. Obstacles encountered so far can be rammed by LCT, and craft can retract and navigate afterward. Greater hazard to craft are the Tellermines, or other attached explosive devices. (These must therefore be neutralized or countermined before ramming.) It is recommended that ramming be considered for obstacle clearance in any further operations. It is quite possible that the enemy will put obstacles below water hereafter, having seen that we chose to attack them above-water in NEPTUNE; and in this case ramming (preceeded by mine clearance) might be the only possible method. 3. Explosive Devices. Whether ramming-technique is used or not, there should be a fixed rule that demolition parties will either countermine or remove Tellermines, artillery shells, and other explosive devices attached to obstacles. (As mentioned earlier, vehicles were damaged by mines apparently fallen from obstacles; and some NCDUs did not actually put a charge on the mines on their obstacles, but relied on shock of blowing obstacles to detonate mine.) 4. Rubber Boat. Under the conditions met by Force 'O', the use of a rubber boat for auxiliary explosives is undesirable. It is easily buliet-holed, it is awkward above the water line, and it forces the men off-loading it from landing craft to gather and stay in one spot, a perfect target. (NCDU 141 virtuaily wiped out by machine gun fire while unloading rubber boat; NCDU 23 wiped out by shell-hit on explosives in rubber boat.) Under the conditions met by Force 'U', the rubber boat was satisfactory. It is recommended, however, that an amphibuous or wading vehicle, such as jeep or weasel, be used as the carrier for auxiliary explosives. 5. Army M-1 Ammunition-Bag. It is recommended that charges and other demolition gear be packed in these bags. Those NCDUs having them report their men were far more free to run, use their hands, and hit the deck than if they had ordinary packs. 6. Short-burning detonating assemblies. If non-electric firing is to be used, each unit should be equiped with shorter-burning, lengths of fuse then the 2 minute fuses generally used. These enable Units to Clear their gaps of personnel and vehicles, and fire their charges before others infiltrate the gap. 7. Dozers for NCDUs. It is recommended dozers be assigned to NCDUs as they were to Army Demolition Teams. Then Naval units will not have to cease mechanical clearance work when Army dozers go inland, as they must very early in any operation. (On OMAHA, NCDUs had to borrow dozers from Seabees; arrangement was mutually unsatisfactory because each group needed dozers at same times, especially at low tides.) OMAHA units feel more dozers could have been used; UTAH units feel enough were on hand. 8. Gap Marking, should not be the duty of the NCDU. A separate party should be trained and equiped for it, working closely with beachmarking groups. They should be exercised and erabarked with NCDUs, however. 9. Gap Markers should be lighter, and harder to puncture, than the can buoys used in NEPTUNE. In several cases in NEPTUNE one can of a pair was punctured by bullets or shrapnel. The plan to use black & red channel markers should also be further considered. Or perhaps black-and-white striped mid-channel markers could be used. Whatever colors & markers are used, the highly vulnerable can-construction should be avoided. 10. Coxswain's Briefing. (a) In future operations, coxswains should be briefed to expect demolitions explosions continuing on the beach after D-day, Some coxswains in this operation apparently mistook the demolition for shelling, (an easy mistake to make), and were afraid to approach the beach. (b) They should also be briefed very forcefully on the effect of Tellermines and similar explosive devices upon their craft. It is believed that many craft, especially among the LCTs, after being holed by Tellermines could have been retracted successfully (at the very least to deep water) instead of being abandoned to obstruct the beach. 11. Post Assault Work of the NCDUs. Work in the post-assault period for the Demolition Units should be definitely provided for in the Operation Order. Either NCDU should be withdrawn at a specified date, or else definitely included in plans for wreck dispersal, channel-blasting, etc. The position of Bomb-Disposal and Mine-Disposal Officers in the NCDUs, with respect to post-assault work in those special fields, should be clarified. It is recommended that regular U.S.N. Bomb and Mine Disposal Officers, who have been spending full time on these highly technical specialties, be put in a position to take over U.S. Naval responsibilities in this field, early after the assault, calling on B.D. and M.D. Officers within NCDU for assistance, as a sort of reserve.