Report No. 51
of the
Operations Evaluation Group
This document contains information affecting the national defense of the United States within the meaning of the Espionage Act, 50 U.S.C., 31 and 32, as amended. Its transmission or the revelation of its contents in any manner to an unauthorized person is prohibited by law.
This volume is classified
CONFIDENTIAL* in accordance with the security regulations of the War and Navy Departments.
* Declassified by Article 0414 of OpNav Instruction 5510.1B
Manuscript and illustrations for this volume were prepared for Publication by the Summary Reports Group of the Columbia University Division of War Research under contract OEMsr-1131 with the Office of Scientific Research and Development. This report was printed and bound by the Columbia University Press and was also issued as Volume 3 of Division 6 in the series of Summary Technical Reports of the National Defense Research Committee. It was originally published in duplicate form on 10 April, 1946, and was given wide distribution within the Navy Department.
Distribution of this volume has been made by the Chief of Naval Operations. Inquiries concerning the availability and distribution of this report and microfilmed and other reference material should be addressed to the office of the Chief of Naval Operations, Navy Department, Washington 25, D.C.
OEG REPORT No. 51
ANTISUBMARINE WARFARE
IN
WORLD WAR IICharles M. Sternhell and Alan M. Thorndike
Operations Evaluation Group
Office of the Chief of Naval Operations
Navy Department
Washington, D.C., 1946
This book consists of a statistical review of the anti-submarine war in the Atlantic
from 1941 to 1945, together with a unified analysis of the tactics which proved most useful
in this combat. It is believed that this material will be of considerable help in providing
basic understanding of this extremely important branch of naval warfare.
Certain aspects of the work of the group, which impinge on the antisubmarine problem,
such as the Theory of Search and Screening and the more general Methods of Operations Research,
will be embodied in other volumes to be published later.
Phillip M. Morse
A clear understanding of the events of World War II, their reasons and consequences,
is necessary, however, as background for any decisions which are to be made in the
postwar period. It is hoped that this volume may serve to some extent as a convenient
reference and source of factual material. One overall conclusion is clearly evident from it:
the introduction of new weapons, gear, and tactics has led to a continual interplay
of measures and countermeasures in which no other conclusion retains its validity for
very long. If this lesson alone is learned from it, the volume will have served a useful purpose.
The general organization corresponds closely to the dual aim described above,
with two parts quite different in character. Part I is a historical summary of
the progress of enemy submarine operations and Allied antisubmarine operations
during World War II. No attempt has been made, however, to give a complete chronology
of all events. The point of view is statistical, and every effort is made to describe
the progress of World War II in quantitative and objective terms. The data are interpreted
in terms of the ever-changing tactical and strategical situation. Accordingly,
the historical summary is divided into seven chronological periods, as indicated
in the Table of Contents. This division is necessary because of the radical changes
in the nature of the U-boat war due to changes in U-boat tactics and the introduction
of new weapons and countermeasures.
The periods were chosen in such a way that U-boat strategy and tactics were fairly
homogeneous in each. The tactics of individual U-boats varied considerably,
however, from the typical characteristics which were common to the operations of
most of the U-boats during the periods in question. In particular the division points
between periods are somewhat indefinite and represent the approximate dates at which
a majority of the U-boats had made a major change in their methods of operation.
The data for a given period are further divided into three main sections.
Part II of the volume is a more detailed analysis of certain of the major problems of ASW,
in particular those which were the subject of operations research studies. The emphasis
is on the evaluation of tactics and matériel both by theoretical analyses and
by special studies of operational data. Although the principles of ASW derived from
such evaluation are strictly applicable only to the situation which obtained during World War II,
the methods of evaluation are of more general interest.
The U-boat war spread over all the oceans of the world, but the main battle was fought
in the Atlantic. Consequently U-boat activity in other regions has not been discussed
as completely as the Battle of the Atlantic. A standard subdivision into areas,
which has been used throughout the text, is given in the frontispiece.
There are, in fact, many aspects of the war which are omitted from the discussion.
The operations of midget submarines and small battle craft are generally excluded,
since they are not considered U-boats. The importance of the training of personnel
and developments along this line are not considered. The activities of Naval Intelligence
in obtaining information upon which operaticns are planned are not described
The sources of material used are so widely scattered through correspondence and informal
memoranda that it has not been practical to quote references to them.
In addition, numerous letters, notes, informal memos, and even oral conversations
go to make up the background of this volume. One of it's chief aims has been to
set down in writing a fair sample of this store of material whose previous status
verged on that of folklore.
No effort has been made, therefore, to assign credit for the work discussed.
It originatesd with various members of British and United States operations research groups,
military services, and civilian war agencies. We have tried to collect available
information and tell a reasonably unified story, not of the accomplishments of
a particular group, but of the progress of a special type of Naval Warfare.
C. M. STERNHELL
Foreword
Director, Operations Evaluation Group
Preface
in any detail. The indirect effects of factors such as strategic bombings are largely neglected.
The net result is to limit the discussion fairly closely to Navy antisubmarine operations,
though Royal Air Force Coastal Command aircraft and those of the United States Army Air Forces
are included when flying antisubmarine missions. The distinction is not a hard and fast one.
A. M. THORDIKE
Editors
CONTENTS