Short answers, pulled from the story.
David Dixon Porter received his official appointment as midshipman on the 2nd of February 1829. This event marked the beginning of a sixty-two-year career that spanned from childhood to old age.
David Dixon Porter organized a flotilla of some twenty mortar boats to participate in reducing forts defending New Orleans. The bombardment began on the 18th of April 1862, though Farragut decided to bypass the forts on the night of April 24 while the mortars distracted enemy gunners.
David Dixon Porter resolved to change the academy by revising the curriculum to reflect naval life and enforcing strict discipline. He encouraged sports, taught social graces alongside technical skills, installed an honor system, and brought like-minded young officers to the faculty to ensure reforms endured.
George Robeson replaced Adolph E. Borie as Secretary of the Navy and promptly curtailed Porter's powers due to powerful opposition from Congress and political generals. Porter faced these enemies who had contended with him during the war, leading to his removal from active influence even though he reached the mandatory retirement age of sixty-two in June 1875.
David Dixon Porter died on the 13th of February 1891 at the age of seventy-seven. He served on active duty for sixty-two years, which represented one of the longest careers in its history.