In the early stages of the Second World War, Donitz's U-boats generally
adhered to Prize Rules, surfacing before attacking and making every
effort to preserve the lives of their victims' crews. But, with the
arming of merchant men and greater risk of damage or worse, they
increasingly attacked without warning.
So successful was the U-boat campaign that Churchill saw it as the
gravest threat the Nation faced. The low point was the March 1943 attack
on convoys SC122 and HX229 when 44 U-boats sank 22 loaded ships.
The pendulum miraculously swung with improved tactics and technology. In
May 1943 out of a force of over 50 U-boats that challenged ONS5, eight
were sunk and 18 were damaged, some seriously. Such losses were
unsustainable and, with allied yards turning out ships at ever
increasing rates, Donitz withdrew his wolf packs from the North
Atlantic.
Expert naval author and historian Bernard Edwards traces the course of
the battle of the Atlantic through a series of thrilling engagement case
studies.