As the nation’s future hung in the balance, the Weather Gods delivered a wrath of fury on Union and Confederate forces throughout the Gettysburg Campaign. First, record-breaking heat and humidity wore down the warring armies during ungodly forced marches. Next, relentless storms plagued the soldiers with resultant muddy slogs on nearly impassable roads. As the armies met in mortal combat, soul-crushing heat turned the bucolic fields of Gettysburg into a sanguinary and barren expanse. Finally, torrential rains haunted the Confederate retreat and narrow escape across a swollen Potomac River. Authors Jeffrey J. Harding and Jon M. Nese present firsthand accounts, harrowing narratives and groundbreaking meteorological research that reshapes how we view the Civil War’s Gettysburg Campaign.