This would be the siege of Vicksburg. This battle was an important part of the war for the north because it started out a train of victories.
The fall of Vicksburg, Mississippi on July 4, 1863 gave the Union full control of the river from its source to its mouth.
The fall of Vicksburg, Mississippi on July 4, 1863, gave the Union control of the river along its entire length.
Vicksburg
Control of the Mississippi was the big objective. Soon after the fall of Vicksburg in July 1863, the Union controlled the whole river, denying the Confederates all use of this big military highway, and isolating all enemy units to the West of the river.
By the Union capturing Vicksburg and Port Hudson they took complete control over Mississippi river.
Mississippi River
Vicksburg was the last major Confederate stronghold on the Mississippi River because of its strategic location, which allowed control over river traffic and supply routes. Its high bluffs provided a defensive advantage, making it difficult for Union forces to capture. The fall of Vicksburg in July 1863 effectively split the Confederacy, giving the Union complete control of the Mississippi River and a critical victory in the Civil War.
The fall of Vicksburg on the Mississippi, last major Confederate river-port. This isolated all Confederate units to the West of the river.
It deprived them of the use of this important highway for the transport of men and materials. When the whole river was liberated (after Vicksburg), all Confederate units to the west of it were isolated.
The great Confederate fortress located on the Mississippi River was Fort Donelson. It played a significant role during the American Civil War, particularly during the Battle of Fort Donelson in February 1862. The fort's capture by Union forces marked a crucial victory, opening up the Tennessee and Cumberland Rivers for Union advancement into the Confederate territory. Its fall also contributed to the eventual Union control of the Mississippi River.
With the fall of Vicksburg on July 4, 1863, the Federals gained full control of the Mississippi River and thus cut the Western Confederacy (Trans Mississippi District) off from the eastern two thirds of the Confederacy. Control of the Mississippi was vital to the Union's Anaconda Plan which was intended to strangle the Confederate supply lines both foreign and domestic.
In 1863, the Union forces captured Vicksburg, Mississippi, which was a critical stronghold for the Confederacy along the Mississippi River. This victory, along with the capture of Port Hudson shortly after, effectively divided the Confederacy in two, disrupting their supply lines and communication. The fall of Vicksburg marked a significant turning point in the Civil War, enhancing Union control over the Mississippi River.