Estimates of Allied sinkings of U-boats in World War I totaled 

 178 or 3o5 per montho In World War II, the Allies destroyed 

 a total of 783 enemy submarines according to Allied estimates,,, 

 or 846 in all if enemy lists of losses are accepted -- a monthly 

 rate of 10 o 8 on the basis of Allied figures, or 11„8 according 

 to enemy summaries 



As in World War I, it was the ever-increasing U-boat offen- 

 sive which made even more imminent our own involvement in the 

 conflict, It gave unmistakable warning of the task which would 

 face our Navy immediately , and against full enemy strength, on 

 the day war was declaredo Our Army might shun battle until it 

 had been built up to strength. Our Navy could have no such 

 choice o The enemy was poised, ready to strike , and would strike 

 not only our trans-Atlantic and Pacific shipping, but also our 

 coastal ? South American and Gulf traffic, right up to our home 

 harbors o Of what avail to build up an Army of 8 million men 

 if the battle against the U-boat were lost? 



How ready was our Navy to join battle with the U-boat? 

 How well organized was the scientific and technical talent of 

 the country to stand beside the Navy and engage in the inevi- 

 table battle of wits, of measure and counter-measure, with the 

 scientific talent of the enemy? 



These were the questions facing the Navy and the National 

 Defense Research Committee when the latter came into being in 

 June, 1940 „ The answers were not readily foundo 



Scope of This Volume , 



The present volume tells the story of part of the organ- 

 ization which NDRC established in April, 1941 „ It is the story 

 of Division 6 (originally Section C-4) of NDRC, the sub-surface 

 warfare division, which helped fight the U-boat and, when vic- 

 tory over the U-boat was assured, went on to assist our own 

 submarines in the battle of the Pacific „ 



The history, the principal activities and some of the 

 accomplishments of the Division will be recounted in succeed- 

 ing chapters o The story cannot be complete because many of 

 the most important developments are still held secret, so 

 carefully guarded that the enemy does not yet know all that 

 hit him D 



It must be emphasized, too, that this is the story of only 

 one of many research and development agencies, both in this 



