William English Mickle was born on October 31, 1846, in Columbia, South Carolina, to Joseph and Nancy Mickle. His father was a merchant. The family lived in Columbia, until around 1852, when they moved to Mobile, Alabama. He attended Summerville Institute in Mississippi in the early 1860s, and he left school to enlist in the Confederate army on August 20, 1864. He mustered in as a private in Company A of the 3rd Alabama Infantry, and he was severely wounded in the Battle of Cedar Creek on October 19, 1864. He tried to rejoin his regiment a few months later, but the Confederate medical examiner declared that he was still unfit for duty.
He settled in Mobile, Alabama, after the war, and he married Ellen S. Woodhull there on October 7, 1867. They had at least six children: Ellen, born around 1869; William, born around 1872; Louie, born around 1874; May, born around 1877; Caro, born around 1880; and Josephine, born around 1883. He worked as a teacher until 1869, when he became a bookkeeper. By 1910, he was living in his daughter Louie’s household in Mobile. He served as adjutant general of the United Confederate Veterans from 1903 until 1920. He died in Mobile on February 18, 1920.