The quickest way to get past the exclusion zones for the Union Flotilla is to attack 6,21 for Zone 1 (Grand Gulf) and 13,7 for Zone 2 (Vicksburg). The destruction of any Confedrate artillery unit in the target hex will release the respective zone. Alternatively, if any Union gunboat is destroyed, Zone 2 will come down. This simulates the Union Flotilla running past the batteries at Vickburg (Zone 2) and Grand Gulf (Zone 1).

At the time of the Civil War, the Mississippi River was the single most important economic feature of the continent; the very lifeblood of America. Upon the secession of the southern states, the river was closed to unfettered navigation, which threatened to strangle Northern commercial interests. President Abraham Lincoln told his civil and military leaders, "See what a lot of land these fellows hold, of which Vicksburg is the key. The war can never be brought to a close until that key is in our pocket.... We can take all the northern ports of the Confederacy, and they can defy us from Vicksburg." Lincoln assured his listeners that "I am acquainted with that region and know what I am talking about, and as valuable as New Orleans will be to us, Vicksburg will be more so."

The Vicksburg campaign was waged from March 29 to July 4, 1863. It involved over 100,000 troops with battles in west-central Mississippi at: Port Gibson, Raymond, Jackson, Champion Hill, Big Black River and 47 days of Union siege operations against Confederate forces defending the city of Vicksburg.

Located high on the bluffs, Vicksburg was a fortress guarding the Mississippi River. It was known as "The Gibraltar of the Confederacy." Its surrender on July 4, 1863, coupled with the fall of Port Hudson, Louisiana, divided the South, and gave the North undisputed control of the Mississippi River. More importantly, it came on the heels of Lee's defeat at Gettysburg. With these disasters for the South clustered in quick succession, their ultimate doom was not hard to foretell.