What was the last amphibious operation of the Civil War?

The Capture of Fort Fisher, Virginia, is regarded as the last significant amphibious operation of the Civil War. This operation took place in January 1865 and was crucial for the Union forces in attempting to close the port of Wilmington, North Carolina, which was the last major supply line for the Confederacy. The successful capture of Fort Fisher not only reduced the Confederate's ability to receive goods from overseas but also aided in the subsequent Union campaigns in the South.

Amphibious operations were a hallmark of the Civil War, and the tactics used at Fort Fisher represented a culmination of what had been learned throughout the conflict. Unlike some other battles and sieges during the war, the operation at Fort Fisher involved a coordinated assault by naval and land forces, demonstrating the strategic importance of controlling coastal areas.

Other choices, such as the Battle of Gettysburg, the Siege of Vicksburg, and the Battle of Fort Sumter, are significant events in their own right but do not fit the criteria of an amphibious operation. Gettysburg and Vicksburg involved land combat and sieges, while Fort Sumter was primarily a land and artillery engagement, lacking the naval component characteristic of an amphibious operation.