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.

Photograph Taken During Prisoner Exchange Negotiations Between Union and Confederate Officers Under Flags of Truce at Camp Fisk in Vicksburg, Mississippi (1865)

Photograph taken during prisoner exchange negotiations between Union and Confederate officers under flags of truce at Camp Fisk in Vicksburg, Mississippi, April 1865. Many of the wounded Union POWs released as a result of these negotiations died after the boilers of the SS Sultana, the steamship they were traveling back home on, exploded near Memphis, Tennessee, on April 27, 1865.

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View of Confederate-held Vicksburg Said to be Taken While Under Confederate Fire During the Siege of Vicksburg (1863)

"Vicksburg, taken under fire." View of Confederate-held Vicksburg from Union lines across the Mississippi River which was said to be taken while under Confederate fire during the Siege of Vicksburg, 1863. Caption written by Assistant Surgeon George H. Bixby. From Miller’s Photographic History of the Civil War.