based at Malta, and achieved notable successes against warships and merchantmen. Two U boats, stationed in the Sicilian Channel, sank several major Italian merchant ships which were transporting troops and supplies to Africa. Like other British boats, the U Class was particularly successful against submarines. In the Mediterranean alone, five Barrow-boats (Upholder, Ultimatum, Unbeaten, Unruly and United) sank a total of eight submarines: six Italian and two German.
During the war, 19 boats of the class were lost on active service - 13 in the Mediterranean and six in the Atlantic and North Sea. Another submarine, Untamed, sank in May 1943, but was salvaged two months later and returned to service as HMS Vitality. From 1941, numerous boats were ceded to Poland, the USSR, Holland, Norway and Free France, and of these several
