William Beall was born in Bardstown, Kentucky on 20 March 1825. His parents moved from Kentucky to Arkansas where Beall was raised.
Beall was an 1844 graduate of the United States Military Academy. After graduating Beall served in the United States Army. He was first assigned as a brevet second lieutenant with the Fourth Infantry and served on the northwestern frontier. In 1849 he was promoted to second lieutenant and assigned to the Fifth Infantry. He served until 1855 in the Indian Territory and Texas. He was promoted to first lieutenant and then shortly thereafter to captain with the First Cavalry.
Beall was involved in several skirmishes, combats, and expeditions against the Indian tribes in the west. In 1860 he participated in a raid against the Kiowa and Commanche.
At the outbreak of the Civil War Beall resigned his commission as was appointed as a Captain of cavalry in the Confederate Army. Beall served in the Trans-Mississippi Department under General Earl Van Dorn early in the war and was appointed Brigadier General in the spring of 1862.
Beall was placed in command of the Confederate cavalry forces at Corinth, Mississippi.
Beall was placed in command of a brigade made up of troops from Arkansas, Mississippi, Alabama, and Louisiana. Beall was initially in command during the Battle of Port Hudson and surrendered there on 9 July 1863. Beall was taken as a prisoner of war and imprisoned at Johnson's Island Prison Camp in Ohio.
In 1864 Beall was appointed as a Confederate agent for the purpose of supplying Confederate prisoners of war and paroled for this purpose. Beall established an office in New York, New York and sold cotton allowed through the Union blockade of southern ports. The proceeds of these sales were used to purchase clothing and blankets for Confederate prisoners in northern prison camps.
Beall was released on 2 August 1865. He moved to St. Louis, Missouri and became a merchant.
Beall died on 25 July 1883 in McMinnville, Tennessee. Beall is buried at Mt. Olivet Cemetery in Nashville, Tennessee.