Union General Ulysses Grant decided that there was a way to get at Richmond and Lee. A few miles to the south, the city of Petersburg contained crucial rail links supplying the capital. If the Union Army could seize it, Richmond would be taken. Through the fall and winter, both armies constructed elaborate series of trenches, eventually spanning more than 30 miles, as the Union Army attempted to get around the right (western) flank of the Confederates and destroy their supply lines. By March, the siege had taken an enormous toll on both armies, and Lee decided to pull out of Petersburg. He led his army in a desperate dash to Appommatox, hoping to unite with the forces of General Johnston in North Carolina.