Based upon the mount, photographer, content, and lack of a revenue stamp, I would date this cdv as pre September 1, 1864, which is when revenue stamps were first required to be attached to cdvs. This a wonderful image that marries baseball and the Civil War.
The image pictures nine soldiers/cadets in an outdoor pose. A bat is clearly visible in the foreground and the soldier in the upper left is holding a baseball. Finding any baseball related photograph this early is next to impossible to do. After 1865 and the end of the Civil War, baseball related cdvs became more plentiful.
Although still very difficult to find, they were available. Good luck finding another baseball cdv pre-1865 that doesn't cost a large dollar amount. Please feel free to ask any questions. The item "EARLY 1860s BASEBALL CIVIL WAR CARTE DE VISITE CDV" is in sale since Monday, February 19, 2018. This item is in the category "Collectibles\Militaria\Civil War (1861-65)\Original Period Items\Photographs".
The seller is "grp75" and is located in Mount Morris, New York. This item can be shipped to United States.