(dramatic music) - On the 1st through 3rd of July, 1863, the Battle of Gettysburg occurred, and is considered one of the most important engagements of the Civil War.

After a victory over Union forces at Chancellorsville, General Robert E. Lee led his army of Northern Virginia into Pennsylvania in late June of 1863.

On 1 July, the advancing Confederates clashed with the Union Army of the Potomac, commanded by General George G. Mead at the crossroad town of Gettysburg.

The next day saw even heavier fighting as the Confederates attacked both federal flanks.

On 3 July, Lee ordered an attack with approximately 15,000 soldiers on the Union center.

The attack known as Pickett's Charge managed to pierce the Union lines, but eventually failed at the cost of thousands of rebel casualties.

Lee was forced to withdraw his army towards Virginia on 4 July.

The battle was a major turning point for the Union, halting Lee's northern invasion.