The two armies suffered between 46,000 and 51,000 casualties. Union casualties were 23,055 (3,155 killed, 14,531 wounded, 5,369 captured or missing),^[126] while Confederate casualties are more difficult to estimate. The casualties for both sides for the 6-week campaign, according to Sears, were 57,225.^[127] In addition to being the deadliest battle of the war, Gettysburg also had the most generals killed in action. Several generals also were wounded.

Compounding the effects of the defeat was the end of the Siege of Vicksburg, which surrendered to Grant's Federal armies in the West on July 4, the day after the Gettysburg battle, costing the Confederacy an additional 30,000 men, along with all their arms and stores.

On August 8, Lee offered his resignation to President Davis, who quickly rejected it.^[128] The ravages of war were still evident in Gettysburg more than four months later when, on November 19, the Soldiers' National Cemetery was dedicated. During this ceremony, President Lincoln honored the fallen and redefined the purpose of the war in his historic Gettysburg Address.^[129]