New Orleans, the heart of Dixie trade, was captured a year into the war in April 1862, followed by Memphis a month later, effectively damming the Mississippi River and choking the flow of blockade runners and Confederate supplies. In doing so, the Union also inadvertently closed river access to yellow fever, saving the occupying forces from the nightmare of disease and death that historically engulfed New Orleans and the Mississippi delta. Confederate planners fully expected New Orleans to be a headache for the Union.
