I was present, however, just after Pickett’s repulse, when General Lee so magnanimously took all the blame of the disaster upon himself. Another important circumstance, which I distinctly remember, was in the winter of 1863-64, when you sent me from East Tennessee to Orange Court-House with some despatches to General Lee. Upon my arrival there, General Lee asked me into his tent, where he was alone, with two or three Northern papers on the table. He remarked that he had just been reading the Northern reports of the battle of Gettysburg; that he had become satisfied from reading those reports that if he had permitted you to carry out your plan, instead of making the attack on Cemetery Hill, he would have been successful.
Source: From Manassas to Appomattox
Commentary
Portion of a letter from staff officer T.J. Goree to Longstreet relevant to Gettysburg: