Slemmer immediately began to collect armaments from the nearby military posts and prepared to hold out against the growing rebellion.

The 6th New York Volunteer Infantry, commanded by Col. William Wilson, was encamped outside the fort, a short distance east of it.

Gen. Richard Anderson crossed from the mainland to Santa Rosa Island with 1,200 men in two small steamers to surprise the Union troops at Camp Brown and if possible capture Fort Pickens.

He landed on the north beach about four miles east of Fort Pickens and divided his command into three columns.

Fort Pickens and the battle site are preserved within the Gulf Islands National Seashore.