per month, as against 175,000 gross tons of new construction 

 the net loss of 188,000 gross tons per month was 45 per cent 

 less than during the previous period,, Despite this hopeful 

 sign, total net losses for the period brought shipping avail- 

 able to the Allies down to 33,000,000 gross tons at the 

 period's close. 



The anti-submarine escort vessel situation showed improve- 

 ment, British ocean-going escort had risen in number from 375 

 to approximately 500, and the entry of the United States into 

 the war added 175 destroyers to the number of available escorts. 



Period IV: Through September 1942 . 



Period IV of the anti-submarine war, from January 1942 

 to September 1942, found the U-boats extending their range 

 to the very shores of the latest principal participant - the 

 United States. 



During the 9 months of Period IV the U-boats sank 878 

 Allied and^neutral vessels of 4 S 587,000 gross tons, which 

 meant that losses from U-boats averaged 98 ships of 510,000 

 gross tons per month. The world-wide total of enemy submarines 

 sunk during the period was 78, making the exchange rate 11 mer- 

 chant ships of 59,000 gross tons sunk by U-boats for each U- 

 boat sunk* 



During the period, Japanese submarines sank 76 ships, 48 

 in the Indian Ocean and 28 in the Pacific . Japanese submarine 

 losses were 11, or an exchange rate of 7 merchant ships sunk 

 to one submarine lost. In the Barents Sea, on the northerly 

 convoy route to Russia, 15 merchant vessels were lost as 

 against 2 U-boats sunk, The Mediterranean was the only area 

 in which the rate of exchange favored the Allies . There, 21 

 enemy submarines were lost and only 17 merchant ships were 

 sunk. 



But the principal area of battle during Period IV was 

 the Atlantic, where almost 90 per cent of the Allied ship- 

 ping losses occurred and where an average of 57 U-boats at 

 sea sank a monthly average of 85 ships of 456,000 gross tons. 

 During this period the average U-boat at- sea sank one and a 

 half vessels of 8,000 gross tons per month, or 50 per month more 

 than during the previous period. 



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