Most of General Lee’s army of 75,000 reached Gettysburg, Pennsylvania, on the evening of July 1. Most of the 90,000-man Union army of General George Meade arrived at Gettysburg that same evening. On July 2, Lee tried to attack Union positions from the left and right flanks, but Union troops repelled the attack. The next day, the Union army, which expected Lee to attack again on the flanks, reinforced its flanks. But Lee launched a frontal attack on the center of the Union lines, which came as a shock and a surprise. Some 15,000 Confederate...