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." US 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 move up the Mississippi. Memphis fell to Union forces on June 6, 1862, allowing it to serve as a key base for further Union advances south along the Mississippi. On the Mississippi River, the Union took every fortress city with the exception of Vicksburg, Mississippi. But Confederate control of Vicksburg was sufficient in preventing the Union from controlling the entire river.