Isaac Shelby was born around 1840 in Mississippi to Moses and Mary Shelby. His father was a planter who owned $8,000 of real estate by 1850. He grew up and attended school in Claiborne County, Mississippi, and he probably moved to Bolivar County, Mississippi, in the 1850s. He graduated from the University of Mississippi in 1860.
He enlisted in the Confederate army on August 9, 1861, and he mustered in as a private in Company E of the 28th Mississippi Cavalry. According to his service records, he was 5 feet, 9 inches tall, with light hair and blue eyes. He earned a series of promotions, and he eventually became a captain. A eulogist later described him as a “gallant and courageous officer.” Union forces captured him at Pulaski, Tennessee, on December 25, 1864, and he spent the next few months imprisoned at Fort Delaware. He swore an oath of allegiance to the Union on June 9, 1865.
Shelby returned to Mississippi after the war, and he married Ella Poitevent on May 30, 1866. They had at least four children: Moses, born around 1866; Mary, born around 1868; Ellen, born around 1872; and Isaac, born around 1874. They lived in Bolivar County, and Shelby worked as a farmer. By 1870, he owned $20,000 of real estate and $5,000 of personal property. According to one local writer, “No man in the county was better known [and] no one [was] more respected.” He contracted a “malarial fever” in the fall of 1833, and he died near Concordia, Mississippi, in October 1883.