
Welles assigned the Gulf Blockading Squadron to patrol 1,500 miles of coastline from Key West to the border with Mexico. In May 1861, Secretary of the Navy Gideon Welles established two squadrons to enforce the blockade and prevent the trade with the South. A small percentage of cotton continued to be exported by Confederate blockade runners. On 19 April 1861, President Abraham Lincoln declared a blockade of all Southern ports, designed to prevent the export of cotton or the illegal import of weapons and supplies. They also captured its companion fort, Fort Gaines, which was a work in progress and without a garrison. Eight days before Alabama seceded from the United States, state militia moved in to take control of Fort Morgan, which guarded the main shipping channel leading into Mobile Bay.

The state of Alabama seceded from the union in January 1861, and Mobile became the fourth-largest city in a new confederacy. It was the 27th-largest city in the United States prior to January 1861.

The city of Mobile, the only seaport in the state of Alabama, exported more cotton than any city in the United States except New Orleans. Cotton was its chief crop and the most valuable export in the United States. In 1860, the South was a predominantly agricultural society.
