The following year, the Union Army of the Gulf commanded by Major General Nathaniel P. Banks laid siege to Port Hudson for nearly eight weeks, the longest siege in US military history. To cut Port Hudson's supply lines through the Red River, Banks first advanced up Bayou Teche, capturing the Atchafalaya and the Red rivers up to Alexandria. (See Bayou Teche Campaign.) The Confederates defending the city surrendered on July 9, after hearing of the surrender at Vicksburg. These two surrenders gave the Union control over the entire Mississippi River and split the Confederacy in half.