Answer:
Vicksburg surrendered because, as a result of the siege, both Confederate soldiers and the people of the city were running out of food and supplies.
Step-by-step explanation:
The Siege of Vicksburg was a great battle fought in the context of the Vicksburg Campaign during the Civil War.
After two major frontal attacks (May 19th and 22th) against Confederate lines were repelled with heavy losses, General Grant decided to initiate a prolonged siege of the city on May 25. With no reinforcements and little supplies, the Confederates were still able to resist for a little over forty days, but were forced to surrender on July 4th. Five days later, another Confederate army surrendered to the Union at Port Hudson. With this, federal government troops took complete control of the Mississippi River.