(1900 - 1986) American admiral responsible for the construction of the 'Nuclear Navy', starting with the submarine Nautilus. Great content T.L.S. on USS GREENLING letterhead, 1p. 4to., 'At Sea, North Atlantic', July 25, 1967. This letter, sent to an associate of powerful Vermont Sen. George D. Aiken, details the first sea trials of the USS GREENLING, '...our 29th attack type nuclear submarine...the second United States Submarine to bear this name..'. Rickover writes that the vessel '...successfully completed all tests, including full power operation, both surface and submerged...', briefly describes the service of the previous ship to bear the name, and states in part: '...The new GREENLING'S primary mission is to detect, track, and destroy enemy submarines..' The unlimited cruising radius, high speed, and quietness provided by nuclear propulsion...make her a most effective anti submarine weapon.' He signs at the conclusion in black ink. Shows original mailing folds, else fine. With transmittal envelope.