On July 2, 1863, the second day of Battle at Gettysburg, a crisis was at hand for the Union army. General Daniel E. Sickles, commanding the Third Corps, had moved his men off higher ground, which included Little Round Top, and created a line running from the Peach Orchard to Devil's Den. This placed the Union left flank open for an attack. Chief Engineer General Gouvernur K. Warren atop Little Round...