Answer:
When two major assaults against the Confederate fortifications, on May 19 and 22, were repulsed with heavy casualties, Grant decided to besiege the city beginning on May 25. After holding out for more than forty days, with their supplies nearly gone, the garrison surrendered on July 4.
Step-by-step explanation:
In the spring of 1863, General Ulysses S. Grant conceived a bold new plan: By marching his Army of the Tennessee down the Mississippi River on its western bank, he could cross the river and approach Vicksburg from the south, giving his troops a more favorable position.