Orlando was born on December 8, 1843 in Douglas, MA to shoemaker and trader Comfort and Mary J. (Simmons) Carpenter. He had an older brother named Merrill Edwin who was born about a year before him who died young, so Orlando was his parents' oldest surviving child. His siblings included Julia Ann, Edwin Cook, Mary A., Herbert Irving, and Alice Jane. He enlisted as a Private into Company B of the 25th Massachusetts Infantry on September 30, 1861 a few months before his 18th b