Two Photographs of Union Soldiers Posing With a Captured Confederate 18-Pounder Cannon Nicknamed “Whistling Dick” (1863)

Two photographs of Union soldiers posing with a captured Confederate 18-pounder cannon nicknamed “Whistling Dick.” The gun was responsible for sinking the Union gunboat USS Cincinnati during the Siege of Vicksburg on May 26, 1863.

Source.
Second image from Miller's Photographic History of the Civil War.