Death in the Doldrums, U-Cruiser Actions Off West Africa, by Bernard Edwards

With their very long range, the giant Type IX U-Cruisers gave Admiral Donitz's U-boat fleet global reach during the Second World War. Initially these boats operated with considerable success off the East coast of America and in the Caribbean but their main impact was in the Gulf of Guinea between 1942 and 1943 which, due to the closure of the Suez Canal, was a vital Allied supply route. Two submarines in particular (U-68 and U-505) had a profound effect, causing major panic by their hugely successful operations.