After the Federal siege of Vicksburg, Mississippi during the Civil War that lasted from May 18, 1863 to July 4, 1863, the Confederates surrendered Vicksburg. It was the climax to the Vicksburg Campaign which was the Federals' attempt to relinquish the stronghold of the Mississippi River that the Confederates held through Vicksburg. Instead of attacking from the river, the Union chose to attack from land on the east side of river. The Confederates, trapped behind the fortress of the city and starving with no help coming for their aid, General John C. Pemberton had no choice but to concede to the Union. Consequently, General Grant essentially won the war for the Union by gaining control of the Mississippi River. Control of the Mississippi River was crucial to the long term success of the army that controlled it. It was a huge transportation resource and with control of the river, an army could quickly send support to its regiments in need faster than it could by foot.