Devils Den is a boulder-strewn Gettysburg Battlefield hill which first gained notoriety for being an important Civil War site and battleground on July 2, 1863 @ the Battle of Gettysburg. Confederates took the Den and began an assault ahead on Little Round Top but were stopped dead in their tracks by Union forces. it is the stuff legends and heroes are made of as witnessed by countless essays, books and biographies of people who made that day and site. Rather than rehash the entire battle with the injustice of a few pieces of prose, go HERE for the full story.
Amid the rocks is a curiosity known as the 
Devil's Den Barricade marked by an interpretive. This stone wall @ Devil's Den represents a defensive shelter used by Confederate Sharpshooters firing across to Little Round Top on July 2, 1863. It is famous for TImothy Sullivan's "staged" July 6th photo of a dead Rebel @ the barricade.
One of the most iconic and recycled photographs about Gettysburg, is this sad scene of a dead Rebel kid/man laying behind a stone barricade at Devil's Den. The photo was taken on July 5 or 6, 1863 by photographer Alexander Gardner and two of associates. Gardner later published the photograph in his "Photographic Sketchbook of the Civil War" accompanied by a lavish description of his discovery of the dead soldier who he described as a sharpshooter killed at his post. Gardner also speculated on the dead soldier's final moments in the sniper's nest, adding that he found his bleached bones still lying in the nest while on a later visit to the site. It was not until 1975 when Gettysburg: A Journey In Time by author-historian William Frassanito was published, that this apparent hoax by Gardner was uncovered. This scene was actually posed by Gardner and his associates who carried the corpse into this position and dressed up the scene with relics of war scattered about the area. A final touch was the rifle standing against the barricade, placed by Gardner who had used the weapon in previous photos. Gardner's assistants, James Gibson and his chief photographer Timothy O'Sullivan, took two photographs of the scene, the clearest of which is shown on the interpretive at this site. They then moved on to photograph other scenes in the adjacent "Slaughter Pen", leaving the body in the sharpshooter's nest. It's kind of a sucky way to die and be remembered and perhaps a bit disrespectful as well. Bottom line here is, I have no doubt this position and barricade were used as a sniping spot as the rocks were piled up in a defensive mode, and a clear view of Little Round Top lay beyond. I was able to see all the monuments from that vantage point.
To truly appreciate this area, it is important to get on a pair of sturdy hiking shows, perhaps a walking stick, and make the trek up, about and around the Den. It will quickly become clear that fir apiece of low ground, this was stil an important an advantageous piece of real estate for protection and for Rebel sharpshooters to pick off Union troops on Little Round Top. Some other tracts of land located here are Houck's Ridge, the Slaughter Pen and Triangular Field, all sites for separate waymarks and documentation.
Children have a particularly fine time here as there are all kinds of places to climb, hide, crawl and leap. There is a stone staircase leading to the top where you will come to a dirt path which wraps around to the back, following Sickles Road below. There are many monuments, markers, memorials and Interpretives to help visitors fully understand and appreciate the tumultuous and deadly evens which occurred here in 1863.
Where there is violent and sudden deaths, ghosts are sure to follow...and stay. The area of the 6,000-acre battlefield reputed to be the most haunted is Devil's Den Ghosts are particularly abundant in the Triangular Field. The 15th Georgia and the 1st Texas Infantry came through the Triangular Field. The fighting was at close range, and the repeated Confederate charges were fierce. The Triangular Field is a favorite spot for ghost hunters. There have been many reports of cameras failing to work there and audio recordings picking up extra sounds perhaps of the ghosts of Gettysburg. SOURCE
Devil's Den got its name long prior to the battle, but no one is sure exactly how. There were apparent ghost sightings there even before the conflict, and unsubstantiated reports of monsters lurking in the rocks. In the decades following those three deadly days in July of 1863, reports of paranormal activity have increased exponentially. Sounds of hoof beats mix with the cries of dying men, and silhouettes dart in between the boulders. Photographs taken show strange orbs of light, and amorphous, swirling forms.
Many visitors have glimpsed an apparition that resembles the typical Texan infantryman of 1863, rough and ragged. He appears briefly, sometimes gesturing or motioning, but never speaking a word. Some speculate that he is the aforementioned sniper who harried the Federal troops on Little Round Top. Another theory centers around a famous photograph which shows a dead Confederate soldier lying supine next to one of the boulders at Devil's Den. This shot was staged three days after the battle by a photographer who dragged the corpse into position. Supposedly, the dead man's spirit resents this disrespectful treatment (Suite101.com). Who this phantom soldier is, or if he is, will probably never be known. But given that over 50,000 men died in that fateful battle, he could be almost anyone. (Gettysburg.com. 11 Oct. 2007)