Table Of ContentDecoding History
Also by W. J. R. Gardner
ANTI-SUBMARINE WARFARE
Decoding History
The Battle of the Atlantic and Ultra
W. J. R. Gardner
Historian
Naval Historical Branch
Ministry of Defence
Foreword by
Geoffrey Till
Dean of Academic Studies
Joint Services Command and Staff College
Bracknell
© W. J. R. Gardner 1999
Foreword © Geoffrey Till 19 99
Softcover reprint of the hardcover 1st edition 1999 978-0-333-69303-2
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Copyright, Designs and Patents Act 1988.
First published 1999 by
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ISBN 978-1-349-40157-4 ISBN 978-0-230-51014-2 (eBook)
DOl 10.1057/9780230510142
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Contents
List of Tables vi
List of Figures vii
Foreword by Geoffrey Till ix
Acknowledgements xii
Glossary xiv
List of Convoys Mentioned in the Text xvi
1 The World War and the Atlantic Campaign 1
2 Chronology, Time and Measurement 17
3 The Economic Context 34
4 A German Perspective 55
5 Convoy Warfare 69
6 Technology on Both Sides 91
7 Signals Intelligence and the Battle of the Atlantic 120
8 Case-Study I: 1941 146
9 Case-Study II: Mid-1942 to Mid-1943 178
10 Conclusion: Evaluating Plays and Actors 210
Notes 219
References and Bibliography 249
Index 257
List of Tables
1.1 The levels of war 3
2.1 Looking at time 23
2.2 War and time 26
6.1 Surface-ship escort - desired characteristics 110
8.1 U-boat fleet growth, mid-1940 to end 1941 149
8.2 Growth in numbers of submarine 173
9.1 Convoy losses by type 186
9.2 Douglas and Rohwer data - comparison 187
9.3 Submarine deployment - 18 March 1943 190
List of Figures
2.1 Closing the air gaps - distance and time 29
3.1 Simplified shipping model 45
5.1 Theory of convoy I 71
5.2 Theory of convoy II 75
5.3 Submarine attack - the ORCA concept 84
5.4 ASW in 1939 - comparative ranges 87
5.5 ASW in 1943 - comparative ranges 89
7.1 High-frequency propagation 122
7.2 Direction-finding accuracy 127
7.3 Decrypt reading times 143
8.1 Tonnage warfare patterns 151
8.2 Convoy and independent losses 153
8.3 Losses by operation type 156
8.4 Productivity flow 161
9.1 Boat-days and tons sunk 193
9.2 Tons sunk per U-boat day 195
9.3 Merchant-submarine exchange rate 198
9.4 Submarine losses 199
Foreword
The Battle of the Atlantic was the great maritime encounter of the
Second World War in Europe. In this campaign, or battle, as it is
usually if confusingly known, a continental power sought to exploit
the vulnerabilities of the maritime coalition that threatened it by
attacking its weakest link, namely the shipping that crossed and
recrossed the broad Atlantic, carrying military equipment and person-
nel and all the requirements of the British war economy. It was one of
the few battles that regularly kept Churchill awake at night, for he
knew how crucial its outcome was for Britain's capacity to survive, let
alone prosecute an offensive war.
It was a huge affair, involving hundreds of U-boats, thousands of
ships, aircraft and people and it lasted for the better part of six years.
Naval personnel on both sides, the merchant sailors of many different
countries, airmen, scientists, code-breakers, logisticians, dockers and
factory-workers all had their crucial roles to play - and suffered accord-
ingly. To use Jock Gardner's own analogy, it was the great maritime
drama of the war and it ran and ran.
Not surprisingly therefore, when confronted with such a huge and
complicated matter, most people seek, and often need, a guide to what
really mattered, to what worked, to what made the crucial difference.
This applies as much to historians bewildered by the mass of some-
times conflicting but always competing data as it does to participants
in the battle who want to understand, or at least to confirm (since they
usually exhibit strong experience-based views on this already), how
their efforts fitted in to the whole.
Accordingly, books about the Battle of the Atlantic usually refine the
complexity and focus on particular aspects of the case. And the ex-
planations came in waves. First was the obvious focus on the dramatic
operational and tactical levels of the campaign, sustained by the pro-
cessing of official Admiralty and German naval records and a flood of
gripping personal reminiscence from both sides. At first this was almost
exclusively the domain of the professional military on both sides, but
soon important contributions to an evolving debate were made by the
chief victims of the battle, the merchant sailors who suffered so much
in the Allied cause. Very soon books which sought to compare and
contrast the role played by the forces of the various nations involved
