George Armistead was born on August 27, 1849, in Baltimore, Maryland, to Charles and Agnes Armistead. His father was a merchant who owned $18,000 of real estate and $10,000 of personal property by 1860. Armistead grew up and attended school in Baltimore, and by 1870, he was working as a bookkeeper. In 1901, he travelled internationally for about a year. According to his passport application, he was 6 feet, 2 inches tall, with brown hair and brown eyes. He died sometime after 1901.