Edited sentence: Allied countermeasures were largely ineffective; the complex arrangements for co-operation between the various navies meant a fragmented and unco-ordinated response, while the main remedy favoured by the Allies for the U-boat menace, the Otranto Barrage, was of little value.During 1916 the commerce war continued unabated.Eight of the top dozen U-boat aces served in the Pola flotilla, including the highest scoring commander of all, K/L Arnauld de la Perière.In 1916 the Allies lost 415 ships, of 1,045,058 GRT, half of all allied ships sunk in all theatres.Just two U-boats were caught in the barrage in all the time it was in operation; meanwhile the merchant ships continued to suffer huge losses