As we continue to observe the Sesquicentennial of the Civil War, the key battles of 1863 will be reviewed.

As we continue to observe the Sesquicentennial of the Civil War, the key battles of 1863 will be reviewed.

President Lincoln's Emancipation Proclamation, which freed the slaves in the states in rebellion against the Union, became effective Jan. 1, 1863. This changed the focus of the war.

CHANCELLORSVILLE: Gen. Joseph Hooker, who replaced Gen. Burnside as Union commander, moved his troops across the Rappahannock River and met the forces of Robert E. Lee 150 years ago today. Facing vastly superior numbers, Lee employed his tactical genius by splitting his forces and attacking the Union on multiple fronts. By this juncture of the war, the uncompromising horrors of the conflict were becoming apparent. Of the 155,000 men engaged, the two sides suffered 24,000 casualties, dead, wounded and missing.

Chancellorsville is regarded as Lee's greatest victory and, in a sense, his greatest loss. While on a night reconnaissance, his most trusted general, Stonewall Jackson, was mortally wounded by one of his own snipers.

GETTYSBURG: With renewed confidence from his stunning, but costly, victory at Chancellorsville, Lee decided to launch his second attempt to invade the North. A chance encounter July 1 at Gettysburg, Penn., led to the most important and most costly of the 2,000-plus engagements recorded in the war. Union forces under Gen. George Mead, newly appointed replacement for Hooker, had superior positions. The failure of Pickell's charge on July 3, which resulted in 6,000 casualties, was the defining moment of the war. Here, more men fought and died than in any battle in American history. Of the 170,000 men involved, casualties for both forces totaled 51,000. With a population of only 2,400, Gettysburg, among other horrors, was left with 5,000 dead horses. Evacuating the battlefield July 4, Lee's wagon train, loaded largely with wounded, was 17 miles long. Nov. 19, President Lincoln dedicated a portion of the battlefield as a cemetery. His two minute address, one of the greatest speeches ever delivered, followed a two hour oration by the principal speaker.

VICKSBURG: Another staggering blow for the Confederacy occurred July 4 the day Lee began his withdrawal. Gen. John Pemberton surrendered the starving city of Vicksburg and 30,000 men to Gen. Ulysses S. Grant. Grant had instituted a siege of the city May 22, which led to the surrender. This victory was essential to the North in regaining control of the Mississippi River. Grant's brilliance in the Vicksburg campaign further boasted his reputation, which eventually led to his appointment as general-in-chief of all Union forces. I visited Vicksburg July 4, 1967, and the city still was not celebrating the holiday.

From this point, it was clear to both sides that the chances of the South winning the war were remote. The Confederacy did realize another major victory in September at Chickamauga, near Chattanooga, Tenn. While this battle is less remembered than other Civil War engagements, it is second to Gettysburg in number of casualties with 34,000. While the final outcome was reasonably certain, this brutal war continued for another 19 months.

Writing about his visit to the battlefield at Gettysburg, George Will told about this doubting tourist who wasn't convinced that a battle actually took place there because there were no bullet marks on the monuments.

NOTE: John Styron of Granby worked extensively in developing media for the new Gettysburg National Military Park Museum and Visitor's Center. He was a concept developer and scriptwriter for the signature film, "A New Birth of Freedom," narrated by Morgan Freeman. He also produced the Cyclorama Sound of Light Show and various audio and video productions from the causes of the war to reconstruction. Styron will also play a key role in the Sesquicentennial celebration, to take place at the battlefield in July.

Roy Shaver writes a weekly column for the Daily News.