William H. Beaumont was born around 1843 in Adams County, Mississippi, to Franklin Beaumont and Phoebe Greenleaf. His father was a farmer who owned $3,000 of real estate and $4,000 of personal property by 1860. The family moved to Texas sometime in the 1840s, eventually settling in Lavaca, and by the early 1860s, he was working as a “ranchero.”
He enlisted in the Confederate army on October 11, 1861, and he mustered in as a private in Company B of the 1st Texas Cavalry. According to his service records, he was 5 feet, 9 inches tall, with brown hair and blue eyes. The regiment was stationed in Texas for much of the war, and it took part in the Red River campaign. He died sometime after 1862.