Complex sentence: He was appointed from Louisiana to the U. S. military academy, where he was graduated in 1854, assigned to the artillery, and served in garrison, and against hostile Indians till the civil war, during which he was in the subsistence department.
Split into simpler sentences: He was appointed from Louisiana to the U.S. military academy, where he graduated in 1854, was assigned to the artillery, and served in garrison. He then served against hostile Native Americans till the American Civil War, during which he was in the subsistence department.