From NKAA, Notable Kentucky African Americans Database (PIONEERS & PATRIOTS: Anderson County Military Servicemen, Revolutionary War - WWI)

Brooks was born a slave in Anderson County about 1825. At some time prior to 1860, Sheldon was taken from his native Lawrenceburg to a place in the deep south, most likely western Tennessee, where he remained a slave.

In 1863, President Lincoln's Emancipation Proclamation freed all the slaves in the southern states, and soon afterward the government authorized the enlistment of colored regiments for service in the Federal Army during the Civil War.

Brooks was among those former slaves to volunteer. He enlisted in Memphis, Tennessee on  December 22, 1863 as a private in the 1st Tennessee Heavy Artillery Regiment (African Descent), but on April 26, 1864 the unit was re-designated as the 3rd U.S. Colored Heavy Artillery.

At the time of his enlistment, Sheldon stated that he was born about 1825 in Anderson County. He was listed as 5'10" tall with dark eyes and dark complexion.

By December 26, 1863 he was listed as Absent Without Leave, and by January 1, 1864 was listed officially as a deserter. He was later listed as returned in August 1865, but there are no details as to whether he returned on his own or was brought back by the Army.