By 1857, the Louisville & Nashville Railroad lacked only a bridge over Green River to complete through train travel between the two cities. Irish stonecutters John W. Key and sons spent two years constructing the limestone piers, and German immigrant engineer Albert Fink designed and built one of his patented trusses for the span. At 1,075 feet long, it was then the largest iron bridge in the United States. Its strategic importance became clear in 1861, when Union and Confederate armies sought control of vital rail lines and this link could draw northern forces south. In August 1861, after General Simon Bolivar Buckner received orders to destroy it, the Keys, having joined Buckner’s rebel force, set and detonated charges that dropped two spans into the river to deny the bridge to the Union. Three battles and five years of continuous military occupation followed in defense of the bridge, during which armies sometimes laid floors across the rails so men, horses, and wagons could cross in great numbers. After the war, trains continued to use the crossing, and the stone piers that witnessed the conflict still support the bridge today.