I’m here in Jones County, Mississippi, to breathe in the historical vapors left by Newton Knight, a poor white farmer who led an extraordinary rebellion during the Civil War. With a company of like-minded white men in southeast Mississippi, he did what many Southerners now regard as unthinkable. He waged guerrilla war against the Confederacy and declared loyalty to the Union.
In the spring of 1864, the Knight Company overthrew the Confederate authorities in Jones County and raised the United States flag over the county courthouse in Ellisville. The county was known as the Free State of Jones, and some say it actually seceded from the Confederacy. This little-known, counterintuitive episode in American history has now been brought to the screen in Free State of Jones, directed by Gary Ross (Seabiscuit, The Hunger Games) and starring a grimy, scruffed-up Matthew McConaughey as Newton Knight.

https://www.smithsonianmag.com/history/true-story-free-state-jones-180958111/