Stop cheeting and do your homework
You probably mean the battle of Vicksburg, in the American Civil War. According to http://www.answers.com/topic/battle-of-vicksburg, the capture of Vicksburg marked the turning point of the war.
Battle of Vicksburg
Battle of Vicksburg
The battle of Vicksburg
Vicksburg
Vicksburg
Battle of Vicksburg
There was no captain named Vicksburg in the civil war, so no person of that name could have been important to the union or anybody else. Perhaps you are thinking of the battle of Vicksburg, which was critical.
I know one of them is Gettysburg.
Vicksburg - the battle that liberated the Mississippi.
Vicksburg
The answer is arguable. I say that politically, Gettysburg was the most important battle. Strategically, Vicksburg was the most important.