With their very long range, the giant Type IX U-Cruisers gave Admiral Donitz's U-boat fleet global reach. 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 1942-43 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.