In April 1862, the Union Navy captured New Orleans. "The key to the river was New Orleans, the South's largest port [and] greatest industrial center." U.S. Naval forces under Farragut ran past Confederate defenses south of New Orleans. Confederate forces abandoned the city, giving the Union a critical anchor in the deep South. which allowed Union forces to begin moving up the Mississippi. Memphis fell to Union forces on June 6, 1862, and became a key base for further advances south along the Mississippi River. Only the fortress city of Vicksburg, Mississippi, prevented Union control of the entire river.