John McElroy (1846-1929), author and journalist is best known for his memoir Andersonville: A Story of Rebel Military Prisons (1879), where he spent almost fourteen months as a prisoner.

Andersonville was the notorious Sumter County, Georgia State prison camp used during the Civil War where thousands of Union soldiers died by the neglect of their Rebel captors. It soon became known as "Andersonville", named for the nearby train station. The appalling conditions of filth, exposure, and starvation horrified McElroy, and he wrote a journal of his time spent there 1864-1865. His keen journalistic mind for observation and attention to committing details to memory served him well.