What was the turning point of the battle of gettysburg?

The battle of Gettysburg (July 1-3, 1863) is considered the turning point of the Civil War. Gen. Robert E. Lee's defeat by the Army of the Potomac forced his Confederate forces to retreat; they never recovered. Lee was emboldened by his victory in Chancellorsville, Va., in May 1863 and hoped to solidify his seeming advantage in Gettysburg. He was unprepared for the ferocity and strength of the Union forces under the newly named Potomac Army commander, Gen. George G. Meade.

Ithink it's b . narratives cannot be changed by other historians later