their transit to and from the French ports, thus increasing 

 their transit time and correspondingly decreasing the time 

 they could remain at sea. Another technical innovation was 

 the adoption by the British of the "hedgehog," a multiple- 

 spigot mortar mounted on the fore part of an escort ship, 

 which could forward-fire a pattern of bombs armed to explode 

 on contacto 



Notable advances in the use of radar were also made 

 during the period,, Not only was greater experience with the 

 rear bringing in good results, but a new set, Type 271, was 

 devised by the British and was being fitted on their cor- 

 vettes. This was a short wave (10 centimeter) beam-type 

 device and constituted a great advance in radar for anti- 

 submarine purpose So 



During the period a total of 44 enemy submarines were 

 sunk - 22 German and 8 Italian submarines in the Atlantic, 

 6 German and 7 Italian submarines in the Mediterranean, and 

 1 Japanese submarine in the Pacific* 



Despite these losses, the fruits of the intensified 

 German U-boat construction program wore beginning to appear. 

 At the start of the period, with approximately 54 U-boats 

 available, the Germans were able to keep about IP at sea in 

 the Atlantic at all times By the close of the period, the 

 number of available U-boats had risen to approximately 200 

 and the average number in the Atlantic at any one time was 

 about 3 ' , 



At the same time, the e f 'f ecti veness and efficiency of U- 

 boat operations showed a sharp drop » Despite the increase in 

 the average number of U-boats at sea, they were able to sink 

 only about 34 chips of ICC, COO gross tons per month in the 

 Atlantic during Period III, or about 25 per cent less than 

 • luring Period II, This meant that the average U-boat was 

 sinking cnl Tr one ship of about 5 5 000 gross tens per month at 

 sea and was therefore only about one-fourth as effective as 

 in the previous periodo Obviously, the loss in efficiency 

 was due only in part to the success of Allied tactics, and 

 proved that the U-boat fleet could not be expanded as rapidly 

 as it had been without suffering from the use of comparatively 

 inexperienced personnel „ 



The Allied shipping position during Period III showed 

 some improvement o Although losses averaged 303,000 ^ross tons 



69 



