Because of the Confederate victory at Bull Run, the Confederacy looked like it was in a strong position, but it had no resources or reserves with which to press its advantage. The Union, therefore, was able to act after a pause.

In October 1861, nearly one hundred Union vessels, with 15,000 troops aboard, sailed down Chesapeake Bay and into the Atlantic. Many of the ships were scattered in a major storm, but they regrouped and by the beginning of November were attacking the Confederate defenses in and around Port Royal, South Carolina. The defenders wired Richmond frantically, but Jefferson Davis had no troops to spare. First the seacoast forts fell, then the town itself. This was the first solid, incontestable Union victory of the war.