Civil War Union Rear Admiral. Born in Boston, Massachusetts, he was appointed midshipman in 1824, but because of his intelligence and an education that included 2 years at Harvard he qualified for a lieutenancy after only 3 years. He later completed his degree at Harvard, and for much of his naval career devoted himself to scientific work important to the navy. On July 11, 1849, he became Superintendent of the Nautical Almanac Office. In 1854 he received a promotion to Commander. Having left his duties at the NAC on November 23, 1856, he was now head of the Bureau of Detail in Washington D.C., when the Civil War began, helping to plan and organize the South Atlantic Blockade and the expeditions against Hatteras Inlet and Port Royal. During the latter expedition, he served as chief of staff and fleet officer to Flag Officer Samuel F. DuPont, contributing much to the successful attack of November 7, 1861. Though he officially replaced Andrew H. Foote as flag officer of the Mississippi flotilla on June 17, 1862, he had been in command since Foote's departure in May. On June 6 his flotilla, along with the rams of Colonel Charles Ellet, destroyed or captured all but 1 vessel of the Confederate River Defense Fleet during the Battle of Memphis, resulting in the surrender of the city to him. Joining Rear Admiral David G. Farragut's force before Vicksburg, he took a cautious approach to the Confederate ram Arkansas, which had passed through the Union fleet and reached the city. Farragut wanted a more aggressive flag officer, as did Secretary of the Navy Gideon Welles. In fact, Welles regarded him as "more of a scholar than a sailor." On October 1, 1862, Commodore David D. Porter was promoted to head a reorganized Mississippi Squadron. Assigned once again to Washington D.C., he resumed his scientific studies. In February 1863 he was promoted to Rear Admiral and in that same year he became one of the founders of the National Academy of Sciences. He also was the author of the works: The Coast Survey of the United States and Narrative of the North Pole Expedition of the USS Polaris. On April 28, 1865, he became Superintendent of the Naval Observatory serving until May 15, 1867, and in his last duty serving in the position again from February 23, 1874, until his death. In February 1911, he was honored with a statue at Vicksburg.