The Eastern Theater of the Civil War saw the bloodiest and most famous battles, as well as the biggest losses, giving the Iron Brigade a chance to demonstrate its mettle during legendary confrontations with Robert E. Lee's Army of Northern Virginia, particularly at the battles of Second Bull Run, South Mountain, Antietam, and Gettysburg. In fact, the brigade suffered the highest percentage of casualties of any brigade in the Civil War, rendering it almost incapable of maintaining a fighting force by June 1864, during the middle of Ulysses S. Grant's Overland Campaign.
General Thomas Jonathan Jackson and his brigade earned the nickname "Stonewall" at First Manassas by turning the tide of that battle, and they would become known as the legendary foot cavalry by bottling up 3 different Union armies in the Shenandoah Valley in 1862. Although Stonewall Jackson and the Stonewall Brigade may share the most famous nickname to come out of the Civil War, it's still unclear whether Barnard Bee, the general who provided the legendary name at First Manassas, meant it as a complaint that they were not moving or as a compliment for standing resolute in the heat of battle.
Regardless, the Stonewall Brigade went on to fight in every major battle in the Eastern theater of the American Civil War, to the extent that of the 6,000 men who fought with the brigade over the course of four years, less than 200 remained by the time General Robert E. Lee surrendered at Appomattox Courthouse on April 9, 1865. They were organized, trained, and mentored by one of the most revered military leaders in American history, and they made a decisive impact on battles like First Manassas, the 1862 Valley Campaign, and Chancellorsville. The brigade was virtually a spent force by the end of the Battle of Spotsylvania Courthouse in May 1864, which took place nearly a year after Stonewall Jackson himself had been mortally wounded at Chancellorsville.
