Signal Rock, known today as Devils Den, anchored the left flank of Union Major-General Daniel E. Sickles' Third Army Corps on July 2, the second day of battle at Gettysburg.

Sickles allegedly advanced his corps against the wishes of Union Army Commander Meade, creating a bulge in the Union line running from the Trostle Farm (location of the right wing), through the Peach Orchard, over the crest of Rocky Hill, around the Wheatfield, and ultimately, Signal Rock (Devils Den).

In what amounted to a Gettysburgian "Battle of the Bulge," the Confederates were quick to assail this exposed position at all points, with Confederate General John Bell Hood leading the attack to take Devils Den, launching his assault from what is known today as the "Triangular Field."

About 4 p.m., Hood's Texas, Arkansas and Georgia regiments collided with the Union's 4th New York Battery and Brigadier General Hobart Ward's brigade attempting to defend this high ground.

The vicious assault was described by one observer as "full of smoke and fire, and literally swarming with riderless horses and fighting, fleeing and pursuing men. The wild cries of charging lines, the rattle of musketry, the booming of artillery and the shrieks of the wounded were the orchestral accompaniments of a scene like very Hell itself."

At one point, the Union commanders at the rocks were convinced the Confederates were falling back. Union Major James Cromwell yelled, "The day is ours," and was immediately shot dead. Union Colonel Augustus Van Horne Ellis also stood in his saddle to direct what he hoped would be a Union counter-charge, and received a Southern bullet between the eyes.

The Confederates had only fallen back momentarily. Then, some of the Union troops on the rocks heard the last sound they would live to hear aside from the thunder of the muskets, the noted "rebel yell." The Confederates launched a final charge to take the rocks, sweeping the Union survivors off the high ground, capturing three of the cannon, and inflicting 781 casualties on Ward's brigade in the process.

Some Confederate units actually over-ran portions of Plum Run and the base of Little Round Top (now known as the Slaughter Pen and its immediate environs) in the drive.

The Confederate troops had won the battle for Devils Den, but the Southern troops who held the Slaughter Pen were not necessarily thrilled with their newly acquired position.

Pinned down by Union sharpshooters and artillery fire in the Slaughter Pen, Confederate 5th Texas Major J.C. Rogers received a message from General Law, "General Law sends his compliments, and says hold the place at all hazards."

Rogers replied, "Compliments Hell! Who wants compliments in such a damned place as this?"