The Union strategy to gain control of the Mississippi, and cut the Confederacy in two parts, was successful at the battle of

A Antietam

B Gettysburg

C Vicksburg

D Fort Sumter

The correct answer is C. The Union strategy to gain control of the Mississippi, and cut the Confederacy in two parts, was successful at the battle of Vicksburg.

Explanation:

The Battle of Vicksburg took place from May 19 to July 4, 1863 around the small town of Vicksburg, Mississippi. It was the last battle of the Second Vicksburg Campaign and is considered a crucial battle of the Civil War.

The battle began with two unsuccessful attacks by the Union's Tennessee army on the Confederate positions outside Vicksburg. Ulysses S. Grant then began to siege the city, which after six weeks and one day on Independence Day resulted in the surrender of the Confederate Mississippi Army defending the city. With the fall of Vicksburg, the Confederation lost its penultimate base on the Mississippi. With the subsequent surrender of Port Hudson, Louisiana, the entire Mississippi Valley was under Union control, and the Confederation was split in two.