Early life and education
Hill, known to his family as Powell (and to his soldiers as Little Powell), was born in Culpeper, Virginia, the seventh and final child of Thomas and Fannie Russell Baptist Hill. Powell was named for his uncle, Ambrose Powell Hill (1785–1858), who served in both houses of the Virginia legislature, and Capt. Ambrose Powell, an Indian fighter, explorer, sheriff, legislator, and close friend of President James Madison.
Hill was nominated to enter the United States Military Academy in 1842, in a class that started with 85 cadets. He made friends easily, including such prominent future generals as Darius N. Couch, George Pickett, Jesse L. Reno, George Stoneman, Truman Seymour, Cadmus M. Wilcox, and George B. McClellan. His future commander, Thomas J. Jackson, was in the same class but the two did not get along. Hill had a higher social status in Virginia and valued having a good time in his off-hours, whereas Jackson scorned levity and practiced his religion more fervently than Hill could tolerate. In 1844, Hill returned from a furlough with a case of gonorrhea, medical complications from which caused him to miss so many classes that he was required to repeat his third year. Reassigned to the class of 1847, he made new friendships in particular with Henry Heth and Ambrose Burnside. Hill continued to suffer from the effects of VD for the rest of his life, being plagued with recurrent prostatitis, which was not treatable before the advent of antibiotics. He may have also suffered urinary incontinence due to inflammation of the prostate pressing on his urethra, which could also lead to uremic poisoning and kidney damage. He graduated in 1847, ranking 15th of 38. He was appointed to the 1st U.S. Artillery as a brevet second lieutenant. He served in a cavalry company during the final months of the Mexican–American War, but fought in no major battles. After some garrison assignments along the Atlantic seaboard, he served in the Seminole Wars, again arriving near the end of the war and fighting various minor skirmishes. He was promoted to first lieutenant in September 1851.