And then July 3 dawns, and the battle that some say will decide the war. General Lee has fewer men than General Meade. That doesn't scare Lee; he has been outnumbered before. The Confederates begin by blasting the Union line with two hours of nonstop artillery fire. Major General George E. Pickett has arrived in Gettysburg with fresh Rebel troops. He will lead the most famous charge in American history—across three-fourths of a mile of open fields. It is an awesome sight. Line after line of gray-uniformed men march out of the woods. Elbow to elbow, like a grand parade, 15,000 fighters step forward in an incredible, orderly, moving rectangle almost a mile wide and half a mile deep . It is eerily quiet. Captain W.W. Wood is among the attackers. He later writes: "We believed the battle was practically over, and we had nothing to do but march unopposed to Cemetery Hill and occupy it."

On the heights, Union General Winfield Scott Hancock gives a hushed order: "Let them come up close before you fire, and then aim low and steadily."

Then suddenly the order comes for the Union artillery to fire. The cannons shoot more than cannonballs. The Union firepower includes cans that explode and send off a hail of metal that murders the oncoming soldiers. Bravely they close ranks and keep coming. The Confederates, a tight mass of men in light gray uniforms, are caught in deadly fire. The Yankees are shooting at them from different angles all along Cemetery Ridge. This is a massacre. A Union soldier from Massachusetts describes it: "Foot to foot, body to body, and man to man they struggled and pushed and strived and killed. The mass of wounded and heaps of dead entangled, hatless, coatless, drowned in sweat, black with powder, red with blood."

The charge is over. And so is the battle . The Confederates have lost one-third of their army; that's 28,000 men . When news of the victory at Gettysburg arrives in Washington on the Fourth of July, the city celebrates. In a few days people will learn that on this same July 4, Union General U.S. Grant has also won a major victory, in Mississippi.

Like his Confederate counterpart Stonewall Jackson, Ulysses S. Grant is a leader who has only one goal: to win. And he knows when and how to break the rules. In Mississippi, back in May, Grant moved his army where no one thought an army could be moved. He left his supply base (no general is supposed to do that) and laid siege to Vicksburg . The navy blocked the river entry to the city. Vicksburg's citizens were trapped. Then cannons began shelling the city. The siege lasted forty-eight days. Dora Miller was one of those trapped inside. She wrote: "We are utterly cut off from the world, surrounded by a circle of fire. The fiery shower of shells goes on, day and night."

Before the siege was over the people of Vicksburg were eating rats—and anything else they could find. Grant starved and bombed them into surrender. The 30,000 Confederate soldiers in the city surrendered, too. Control of Vicksburg means control of the Mississippi River. Those two victories—Gettysburg and Vicksburg—reverse the war .