Culp's Hill, located on the right end of the Union army's position on the second and third days of the Battle of Gettysburg, has kind of left the popular lexicon of the battle. It is a wooded hill, overgrown with trees and thick underbrush. Visitors to the battlefield often overlook it for some of the more famous, more open vistas of the park. However, Culp's Hill was an important part of the Battle of Gettysburg and saw the longest sustained combat action of the entire battle on the morning of July 3.

In 1863, Culp's Hill was covered with trees but the presence of cattle kept the underbrush to a minimum which meant the hill was easily navigable and not much of a hassle when it came to keeping troop formations. The hill itself was actually two hills with a lower and an upper crest. The soldiers of the Union Twelfth Corps occupied this position on the morning of July 2. At the right end of this position were the soldiers of the brigade of Brigadier General George S. Greene. At age 62, he was the oldest soldier in the Army of the Potomac. He also knew his shite.

When his men took position on the extreme right flank of the Union army that morning, he ordered them to begin entrenching. Other Twelfth Corps units took their lead from Greene's brigade and also began to follow suit. When fighting erupted on the left end of the Union line, however, the vast majority of Twelfth Corps units were called to the south to reinforce the Third, Fifth, and Sixth Corps that were fighting against Longstreet's assaulting columns. Only the brigade of George S. Greene remained to defend the right flank of the Union army.

And on the evening of July 2, 1863, a rare night action occurred as Confederates of Edward Johnson's division assaulted Greene's fortified positions on lower Culp's Hill. Despite numerous attempts to take the positions occupied by Greene's outnumbered soldiers, darkness and the imposing entrenchments Greene's men had constructed allowed the Union soldiers to hold on throughout the night. Though some of the entrenchments on lower Culp's Hill were occupied by Confederate soldiers, it was decided by the Union high command that those would be dealt with on the morning of July 3 when the entirety of the Twelfth Corps would launch an attack against the Confederates in its front.

Thus, on the morning of July 3, 1863, the Twelfth Corps - now fully returned from the left flank of the Union line - launched a massive assault against the Confederates on lower Culp's Hill. The resulting action would be the largest and longest of the Battle of Gettysburg. Fighting would last from dawn until about noon and would involve well over 20,000 soldiers from the two armies. At the end of it all, the Union Twelfth Corps held the hill as Confederates under Richard S. Ewell's command had failed to make a dent in the formidable defenses.

The Battle of Gettysburg was thus effectively over. However, Robert E. Lee wanted to try one last thing before admitting that he had been thwarted. Both Union flanks had been attacked and were deemed too strong to be taken. Therefore, Lee theorized, the weak point of the Union position was in its center. That would be the focal point of Confederate efforts on the afternoon of July 3, 1863. With the heat index soaring to above 100 degrees Fahrenheit, the stage was now set for an attack that has gone down in history as Pickett's Charge.