The Port of Apalachicola was of primary strategic importance during the United States Civil War.
Union forces established a blockade of the port on 11 June, 1861, with the USS Montgomery. At times, the blockade employed a squadron of three or more vessels in the area. On 3 April, 1862, a landing at Apalachicola was achieved without resistance from the Confederacy. The port continued to change hands repeatedly throughout the war, usually without serious conflict.