The document discusses the Siege of Vicksburg during the American Civil War. Union forces besieged the city of Vicksburg, Mississippi for 48 days in 1863 to gain control of the Mississippi River. During the siege, inhabitants took shelter in caves and mules were brought in for food. On July 4, 1863, the city surrendered, severing Confederate supply lines. The fall of Vicksburg was a significant victory for the Union as it allowed them to control the Mississippi River. The document then discusses the Battle of Gettysburg in 1863, where Confederate troops engaged Union forces but were defeated, marking a turning point in the war.