How did union forces eventually defeat vicksburg?
a) they dammed the mississippi river.
b) they prepared four frontal assaults.
c) they laid siege to the city for many days.
d) they attacked from the vulnerable river.

C. They laid siege to the city for many days is the correct answer.

Explanation:

The victory of the Vicksburg was one of the greatest victory of the Union as the Union got control of the Mississippi river. At the same time General Robert E. Lee was also defeated at the Battle of Gettysburg.  

General Grants army reached Vicksburg on May 18, 1863 and faced General Pemberton. Pemberton and his  soldiers were hiding behind the defences of the city. At first Grant tried to break in the city  but it didn't work so he decided to besiege the city and starve the confederate soldiers. General Pemberton was finally defeated and the soldiers surrendered on July 4, 1863

c. had saved colonel cresap's family from attack by other native americans.