Total Undersea War

During the last year of World War II the once surface-bound diesel-electric U-boat ushered in the age of ''total undersea war'' with the introduction of an air mast, or ''snorkel'' as it became known among the men who served in Dönitz''s submarine fleet. U-boats no longer needed to surface to charge batteries or refresh air; they rarely communicated with their command, operating silently and alone...