/A16-3
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 report.


Enclosure (A) is forwarded in accordance with reference (a).
A.D. STRUBLE,
Chief Of Staff.



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File No.
CTF122/A16-3

Serial: 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 June, 1944 and endorsements thereto.
Enclosure: (1) Report on the work of the U.S. Naval Combat Demolition units in operation NEPTUNE.


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.
Some of the material collected has been briefed to make up the report which forms Enclosure (1) of this letter.
Respectfully submitted,
(signed)
H.L. BLACKWELL, JR.
Lt. (jg), USNR



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REPORT ON


NAVAL COMBAT DEMOLITION UNITS [NCDUs]


IN


OPERATION "NEPTUNE"


as part of


TASK FORCE 122

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



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TABLE OF CONTENTS

Section I Chronological sketch of NCDUs in U.K. November 1943 -- June 6, 1944
Section II The Operation.
A. Brief Summary.
B. Force OMAHA.
C. Force UTAH
Section III Recommendations for Future Operations.
A. General, for NCDU work under any circumstances.
B. Recommendations Specifically for Operations similar to NEPTUNE


Enclosures:
(1) Tabular summary of Gap Clearance, D-day, Force '0'. [omitted]
(2) OMAHA Beach Map, with trace to show D-day Gap Clearance. [omitted]
(3) Tabular summary of Gap Clearance, D-day, Force 'U'. [omitted]
(4) UTAH Beach Map, with trace to show D-day Gap Clearance. [omitted]
(5) Table of Methods used (Obstacle, Charge employed, Results)
(6) Demolition Operation Order, Force '0'.
(7) Demolition Operation Order, Force 'U'.




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SECTION ONE

CHRONOLOGICAL SKETCH

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.

Sketch history
31 Oct. 1943 ? NCDU #11 Arrived in U.K. ordered to Falmouth.
15 Dec. ? 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 officer. 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 [Eleventh Amphibious Force].
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 Officer 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 by Lt.(jg) C.P. Hagenson CEC-V(S) USNR, primarily for use on steel obstacles (plasticity, small production of shrapnel, ease of attachment, etc.). [This charge commonly referr