Nimitz was the leading US Navy authority on submarines .

Qualified in submarines during his early years, he later oversaw the conversion of these vessels' propulsion from gasoline to diesel, and then later was key in acquiring approval to build the world's first nuclear-powered submarine, USS Nautilus, whose propulsion system later completely superseded diesel-powered submarines in the US. He also, beginning in 1917, was the Navy's leading developer of underway replenishment techniques, the tool which during the Pacific war would allow the US fleet to operate away from port almost indefinitely. The chief of the Navy's
Bureau of Navigation in 1939, Nimitz served as Chief of Naval Operations from 1945 until 1947. He was the United States' last surviving officer who served in the rank of fleet admiral.
Early life and education
Nimitz, a German Texan , was born the son of Anna Josephine (Henke) and Chester Bernhard Nimitz on February 24, 1885, in Fredericksburg, Texas, [3] where his grandfather's hotel is now the Admiral Nimitz State Historic Site. His frail,
rheumatic father had died six months earlier, on August 14, 1884. [4] He was significantly influenced by his German-born paternal grandfather, Charles Henry Nimitz , a former seaman in the German Merchant Marine , who taught him, "the sea – like life itself – is a stern taskmaster. The best way to get along with either is to learn all you can, then do your best and don't worry – especially about things over which you have no control." [5] His grandfather became a
Texas Ranger in the Texas Mounted Volunteers in 1851. He then served as captain of the Gillespie Rifles Company in the Confederate States Army during the
Civil War . [6]
Originally, Nimitz applied to West Point in hopes of becoming an Army officer, but no appointments were available. His congressman, James L. Slayden , told him that he had one appointment available for the United States Naval Academy and that he would award it to the best qualified candidate. Nimitz felt that this was his only opportunity for further education and spent extra time studying to earn the appointment. He was appointed to the Naval Academy from
Texas's 12th congressional district in 1901, and he graduated with distinction on January 30, 1905, seventh in a class of 114.