July 1st, 2nd, & 3rd mark the anniversary of the Battle of Gettysburg fought in 1863 during America's Civil War. Often referred to as the "High Water Mark" for the confederacy because it was here that the tide was finally turns and CSA General Robert E. Lee began his retreat to the South towards Richmond and never again recovered for a major offensive. Another event occurred on July 4th 1863 that also delivered a great blow to the Confederacy. That being the fall of Vicksburg in Mississippi.
Vicksburg Mississippi was essentially the gateway to the Mississippi River being a major port for incoming supplies for the the south. If the Mississippi River could be controlled by the North that supply line for Lees Army would dry up and the Confederate Army would be in dire straits quickly.
A little known General named Ulysses S. Grant had been on a campaign since October of 1862 to encircle the town of Vicksburg and capture it. Several of these attempts resulted in failures and great loss of life for the Union Army as there were several forts and batteries along the river both above and below the town kept the river in Confederate hands and the terrain around the city was difficult. None the less Grant persisted. After several failed direct assaults Grant ordered his army to take up siege operations against the city. This entailed cutting off all lines of supplies and communication to the city as well as a constant artillery bombardment which drove many of the citizens into caves dug into the hillside surrounding the city. All this ended on July 4, 1863 when confederate Lt. General John C. Pemberton surrendered to Grant. Of course this was not relayed to General Lee for several days and it is said that when he found out of this loss he was sure the Confederacy was doomed.
Of even greater importance with this series of events is the victory of Vicksburg brought Grant to the attention of President Lincoln and soon after Grant was appointed to the rank of Lt. General and made the Commander of all Union forces charged with ending the war. It was through this appointment that Grant gave his blessings to General William Tecumseh Sherman to further divide the South with his famed "March to the Sea" taking Atlanta Georgia and soon after Savannah further destroying and depleting the supplies for Lees army that was taking up position around Richmond and Petersburg.
From the Victories at Gettysburg and Vicksburg, new life was breathed into the Union cause and though the war lasted another 18 months after Gettysburg, Lee never again had the momentum to make an offensive action against the Union. Shortly after Lee's surrender to Grant at Appromadox, General Joe Johnson surrendered to General Sherman in the South and essentially the war was over.