Battle of Gettysburg
The nature of the result of the Battle of Gettysburg has been the subject of controversy for years. Although not seen as overwhelmingly significant at the time, particularly since the war continued for almost two years, in retrospect it has often been cited as the "turning point", usually in combination with the fall of Vicksburg the following day. This is based on the observation that after Gettysburg Lee's army conducted no more strategic offensives—his army merely reacted to the initiative of Ulysses S. Grant in 1864 and 1865—and by the speculative viewpoint of the Lost Cause writers that a Confederate victory at Gettysburg might have resulted in the end of the war.
It is currently a widely held view that Gettysburg was a decisive victory for the Union, but the term is considered imprecise. It is inarguable that Lee's offensive on July 3 was turned back decisively and his campaign in Pennsylvania was terminated prematurely (although the Confederates at the time argued that this was a temporary setback and that the goals of the campaign were largely met). However, when the more common definition of "decisive victory" is intended—an indisputable military victory of a battle that determines or significantly influences the ultimate result of a conflict—historians are divided. For example, David J. Eicher called Gettysburg a "strategic loss for the Confederacy" and James M. McPherson wrote that "Lee and his men would go on to earn further laurels. But they never again possessed the power and reputation they carried into Pennsylvania those palmy summer days of 1863."
Abner Doubleday
At the start of the Battle of Gettysburg, July 1, 1863, Doubleday's division was the second infantry division on the field to reinforce the cavalry division of Brigadier General John Buford. When his corps commander, Major General John F. Reynolds, was killed very early in the fighting, Doubleday found himself in command of the corps at 10:50 am. His men fought well in the morning, putting up a stout resistance, but as overwhelming Confederate forces massed against them, their line eventually broke and they retreated back through the town of Gettysburg to the relative safety of Cemetery Hill south of town. It was Doubleday's finest performance during the war, five hours leading 9,500 men against ten Confederate brigades that numbered more than 16,000. Seven of those brigades sustained casualties that ranged from 35 to 50 percent, indicating the ferocity of the Union defense. On Cemetery Hill, however, the I Corps could muster only a third of its men as effective for duty, and the corps was essentially destroyed as a combat force for the rest of the battle; it would be decommissioned in March 1864, its surviving units consolidated into other corps.