In 1936, the 75th anniversary of the war, we see the first example of a new phenomenon: The Civil War reenactment, as the Battle of Bull Run was refought on the actual site, although not by enthusiasts studiously attired in period garb, but 1,500 U.S. soldiers and Marines of 1936, who were ordered to fight like it was 1861. The 75th anniversary was held in the midst of the Great Depression—and the forces of the New Deal were marshaled on the Manassas battlefield, as well. According to national parks historian John Reid, hundreds of workers from the Civilian Conservation Corps worked to prepare the battlefield for the reenactment and served as ushers to the surprisingly large crowd of 31,000 spectators—only 5,000 of whom were able to be seated in the wooden stand constructed by the CCC and the National Park Service for the event.
The 100th anniversary was supposed to be a big deal, but it fizzled out for various reasons, which you can read about at Smithsonian. Link