A few of the federal soldiers got close to the fort, but Confederate fire kept them pinned down. After darkness, the Union soldiers withdrew. Grant still thought that his army could successfully storm the Vicksburg defenses, and three days later, on May 22, he ordered an attack along the entire line. Sherman ordered his men to attack straight down the Graveyard Road so as to avoid the difficult terrain and Southern obstructions. Additionally, 150 volunteers, carrying wood planks to bridge the ditch in front of the redan and ladders to climb the wall, went ahead of the Federal infantry. Info taken from http://www.nps.gov/archive/vick/sitemap. htm