During the first half of 1863, doubts about the Federal army's ability to defeat the Confederate forces mounted across the North. And when Confederate general Robert E. Lee (1807–1870) led his troops to a spectacular victory at Chancellorsville, Virginia, the North grew increasingly anxious. In July, antiwar feelings combined with anger over many of the wartime actions of President Abraham Lincoln (1809–1865) led to a deadly riot in New York that took the lives of more than one hundred people.

But July 1863 also marked a significant turning point in the Civil War. During the first days of that month, the Union forces won two major battles. In the West, the North's successful siege of Vicksburg, Mississippi, enabled it to establish control over the entire length of the Mississippi River. In the East, the Union victory at the famous Battle of Gettysburg forced Lee to abandon his efforts...