The loss of Vicksburg gave the Union control over the Mississippi River, effectively splitting the Confederacy in two and making it much more difficult for the Confederacy to transport troops and supplies between the eastern and western theaters of the war.
Damage to the Southern economy
Vicksburg was a major shipping center for the Confederacy, and its loss severely disrupted the Southern economy. The Union was now able to blockade the Mississippi River and prevent the South from exporting its cotton and other goods to Europe, which was a major source of revenue for the Confederacy.
Loss of morale
The loss at Vicksburg was a major blow to the morale of the Confederate army and the Southern public. It was the first major defeat for the Confederacy after a string of victories, and it made it clear that the Union was winning the war.
Encouragement to enslaved people to seek freedom
The Union victory at Vicksburg encouraged many enslaved people to seek freedom by escaping to Union lines. This further weakened the Confederate economy and made it more difficult for the Confederacy to fight the war.
International recognition of the Union
The fall of Vicksburg led to the international recognition of the Union by Great Britain and France. This made it more difficult for the Confederacy to obtain foreign aid and support.