The notable military strategy employed during the Siege of Vicksburg in the U.S. Civil War was encirclement and blockade. General Ulysses S. Grant implemented a campaign of attrition, cutting off supplies and reinforcements to the Confederate forces. The siege lasted from May to July 1863, ultimately resulting in the surrender of Vicksburg and granting the Union control of the Mississippi River. This victory was pivotal as it split the Confederate territory in two, significantly weakening their overall military capabilities and boosting Union morale, contributing to the turning tide of the war.