The Battle of Gettysburg, 1-3 July 1863. One hundred and fifty years ago the Army of the Potomac and the Army of Northern Virginia clashed at a farm village that was also an important road junction in southern Pennsylvania, a few miles north of the Mason-Dixon Line. While Gettysburg, the most famous Civil War battle, was a tactical success for the Union, it achieved no Union strategic aim. However, the day after Gettysburg, 4 July 1863, the Union achieved its greatest strategic success of the war when General Grant forced the Confederate Army to surrender the important city of Vicksburg, Mississippi. Once the Confederacy lost Vicksburg it no longer could win the war. Had Lee been able to defeat the Army of the Potomac enough to keep that huge Union army north of the Potomac River, it is possible the South could have hung on until the election of 1864; an election Lincoln may have lost. The loss of Vicksburg, however, cut off wheat, corn, and horses from Texas destined for the Confederate armies; it opened the Mississippi River to Union traffic through New Orleans; and it opened a corridor through Tennessee which Grant used to take Chattanooga that opened the door for the fall of Atlanta. It was Sherman’s victory in 1864 that sealed the November election for Lincoln. Meanwhile, Lee could not contain the Army of the Potomac and General Johnson could not keep Sherman from moving north up the eastern coast. When the Confederate flag was lowered and the National Colors were raised over Vicksburg on Independence Day, 1863, the South had effectively lost the war.