Geology Played Key Role in the End of the Civil War
Depending on your perspective, Mississippi geology was either an aiding ally or formidable foe as Union troops tried to take control of the Mighty Mississippi. It was May, 141 years ago, and Major General Ulysses S. Grant, commander of the Union's Army of Tennessee was again trying to take Vicksburg - a prize long sought by President Abraham Lincoln. Vicksburg, 'the Gibraltar of the Confederacy', fell to Federal forces following a 47-day siege at the end of a long campaign to wrest control of the entire Mississippi River from Confederate hands. But it was the geology of the area that almost proved too much for Union forces. Despite the Confederate's 31,000 men and some 170 artillery pieces, 60,000 muskets and ammunition to match, the geomorphology of Vicksburg provided a more powerful adversary, according to USGS geologist Jim Coleman.
The land around Vicksburg is dominated by high bluffs, cut by perennial streams and rivers. The geologic surface of the area, made of quartz silt, has unique engineering properties, which made for superb fortifications. This high strength, naturally absorbent material withstood months of land and river bombardment from the some of the largest guns in the Federal arsenal. When infiltrators moved to tunnel beneath and detonate dynamite charges under Confederate fortifications, much of the intended damage was confined by the natural properties of the cliff walls.
Finally, in late May, 1863, Gen. Grant's army and naval forces converged on Vicksburg, surrounding a Confederate army under Lt. Gen. John Pemberton. On July 4, Vicksburg surrendered after prolonged siege operations. This was the culmination of one of the most brilliant military campaigns of the war. With the loss of Pemberton's army and this vital stronghold on the Mississippi, the Confederacy was effectively split in half. Grant's successes in the West boosted his reputation, leading ultimately to his appointment as General-in-Chief of the Union armies.
