How did Union forces eventually defeat Vicksburg?

1 Answer

By surrounding Vicksburg and laying siege to the fortified city forcing the Confederate forces defending the city to surrender.

Explanation:

Multiple attempts to conquer Vicksburg failed. Attacks from the north were repulsed.

US Grant marched his troops south of Vicksburg on the opposite side of the Mississippi River. Then the Northern Navy made a daring run past the guns of the fortress with the transports that would carry Grant's troops across the river to attack Vicksburg from the east and south.

In a brilliant campaign Grant defeated the Confederate forces outside of Vicksburg allowing him to surround Vicksburg.
Several direct attacks on Vicksburg by Grant failed. His forces then settled down in a siege on the fortress. The Confederate defenders starving and short of munitions surrender.