Outdoor group albumen. Gettysburg: [Tyson Brothers], 1863. Inscription to verso reading "Head Qs Christian Com". 9 x 6 3/4 in. With unattached mat measuring 9 1/8 x 7 3/8 in. July or August, 1863. 

A group photograph showing the U.S. Christian Commission at Camp Letterman, a Civil War military hospital erected near Gettysburg following the battle that occurred there. According to the New York Public Library, this photo was part of a series by the Tyson Brothers for their collection entitled View from the Battle Field of Gettysburg, July 1st, 2d and 3d (see image ID 1150088). 

The U.S. Christian Commission was established by the National Committee of the YMCA following the First Battle of Bull Run. It provided supplies, medical services and religious literature to the Union during the Civil War, distributing more than $6 million worth of goods and supplies. The Commission consisted of seminary students but also just concerned Christians who wanted to help the war efforts without picking up a weapon. Eventually, a women's auxiliary was even founded to provide additional support (Louisa May Alcott, the author of Little Women, was one of these volunteers in the Ladies Christian Commission). Both men and women were present at Camp Letterman to help the 14,000 Union, and even the 6,800 Confederate, soldiers who were wounded during the Battle of Gettysburg. 

The Tyson brothers, Charles and Isaac, were living in Philadelphia as children when they both became interested in daguerreotyping. Eventually, the two moved to Gettysburg and opened a portrait studio on 16 August 1859, assumedly the first professional photographers in the county. Once the Civil War ensued, Union soldiers visited the Tyson brothers to have their military portraits taken to send to their families. And while they were local to the Battle of Gettysburg, they photographed neither the battle nor any of the dead — ethically, they opposed war, while logistically, they could not afford the supplies possible to take field photographs. Instead, they captured various battlefield sites, such as Camp Letterman in this photograph, focusing on the once-tranquil landscape surrounding their subjects. 

References: 

Historic Camera ("Tyson Brothers, photographers")

[Civil War, Union, Confederate] [Photography, Early Photography, Historic Photography, Daguerreotypes, Ambrotypes, Tintypes, Cased Images, Union Cases, Albumen Photographs, CDVs, Carte de Visites, Cartes de Visite, Carte-de-visite, Cartes-de-visite, CDV, Cabinet Cards, Stereoviews, Stereocards] [Gettysburg, Little Round Top, Culp's Hill, Pickett's Charge, Devil’s Den]