Control of the Mississippi River was of vital concern to both the Union and Confederate forces. By the late summer of 1862, only Vicksburg and Port Hudson, Louisiana, remained under Confederate control. Abraham Lincoln called Vicksburg the "key to the war." The Confederate Army of Vicksburg finally surrendered on July 4, 1862, after 47 days under intensive siege by the Union forces under General Ulysses S. Grant and 14 months after the first attack by Admiral Farragut's warships.