Then Lee relieves Longstreet and the attack commences as Lee has originally ordered:
Lee's orders for day (an oblique attack against Cemetary Hill with all 9 divisions) got watered down a lot, and we ended up with Pickett's Charge.
However, in Lee's original concept of operations Hood's and McLaws' Divisions would also step off moving NE up the Emmitsburg Road (as they were ordered to on the 2nd, before Hood was hit and C&C broke down, leading to the attack drifting onto the Round Tops, ground with no significance). Pickett to their left was also to advance NEE. The Heth/Pender composite division was to advance roughly E (hitting where they historically did hit), Rodes' to the SE, Johnson's to the S, Early's the the SWW while Stuart's cavalry "closed the box". Anderson's division was shifted to Longstreet as a reserve, since 1st Corps had the hardest task.
If successful it would have enveloped the Union Right (11th and 12th Corps) and Centre (1st and 2nd), leaving the left (3rd, 5th and 6th) isolated and on poor ground.
Great plan, poorly executed....