General John Logan CDV A natural and daring leader, "Black Jack" Logan, as he was nicknamed, proved to be one of the best volunteer officers of the war. He distinguished himself under Ulysses S. Grant during the Vicksburg Campaign, where his division was among the first to enter the city, and briefly commanded the Army of the Tennessee after James B. McPherson's death at Atlanta. Logan was a prominent figure in the Western Theater, participating in major campaigns including Fort Donelson, Vicksburg, and the Atlanta Campaign. Despite being replaced as commander of the Army of the Tennessee by William T. Sherman in 1864, his battlefield prowess was undeniable. Post-war, Logan helped found the Grand Army of the Republic and is widely credited as the originator of Memorial Day. No Back mark.