The Library of Congress has a special collection of images, donated by the Liljenquist family, of over a thousand ambrotypes and tintypes taken during the Civil War. Many of these are portraits of soldiers, but also includes pictures of children, families, and personal artifacts.
Tom Liljenquist and his sons Jason, Brandon, and Christian built this collection in memory of President Abraham Lincoln and the 620,000 Union and Confederate servicemen who died in the American Civil War. For many, these photographs are the last known record we have of who they were and what they looked like. See "From the Donor's Perspective--The Last Full Measure" for the full story.
The Liljenquist Family began donating their collection to the Library of Congress, Prints & Photographs Division in 2010 and continues to add to it. In addition to the ambrotypes and tintypes, the collection also includes several manuscripts, patriotic envelopes, photographs on paper, and artifacts related to the Civil War.
What struck me was how young so many of the soldiers were.