In his orders to AP Hill and Harry Heth for Heth’s July 1 advance to Gettysburg with his full division, Heth was ordered to NOT bring on a general engagement.
Why would Lee do this?
He had 2 Divisions of Ewell’s Corps at Heidlersburg just a few miles north of Gettysburg. Much of AP Hill’s Corps was behind Heth on the Chambersburg Pike stretching back up South Mountain toward that town. And Longstreet’s Corps was right behind Hill.
Coddington [page 190-191] says, referring to the message for Ewell’s Corps to concentrate on Heidlersburg:
“Although Lee’s second message to Ewell arrived too late to change Johnson’s route, it came in time to divert Rodes to Heidlersburg. He started out on the morning of the 30th and had a “very fatiguing march through rain and mud,” twenty two miles by way of Petersburg [York Springs]. Meanwhile Early, who was still in York with his division of the Second Corps, received word of the change of plans late on June 29. Captain Elliott Johnston of Ewell’s Staff brought him what was obviously a copy of Lee’s first note and verbal instructions to rejoin the rest of the corps on the “western side of the South Mountain,” instead of near Carlisle as had been previously instructed to do. The next morning Early started his command on the Weigelstown and East Berlin Road leading to Heidlersburg. He expected to go to Arendtsville and thence either to Shippensburg or to Greenwood `as circumstances might require.’ On the march he received another dispatch from Ewell and as directed, encamped his men three miles east of Heidlersburg on the road to East Berlin. Then he himself rode to Heidlersburg to confer with Ewell, who had accompanied Rodes’s division down from Carlisle. It was there that Early learned of Lee’s second message to Ewell ordering his division to a rendezvous with Rodes at Heidlersburg.
“This message had an important result which Lee perhaps anticipated but did not mention. With the Second Corps, or a major portion of it, at Heidlersburg the Confederates would be able to approach Gettysburg from two directions should an engagement occur in that area…
“Ewell’s response to Lee’s directives was prompt and efficient. In one day he brought together two of his divisions, which were miles apart, without a hitch…
“While at Heidlersburg on June 30 Ewell heard from A.P. Hill that the Third Corps was at Cashtown, and he decided to move toward it. The next morning, not aware of any emergency, he got both divisions off to a reasonably early start, on two different routes so as to avoid overcrowding the roads. Rodes went almost directly west by way of Middletown [Biglerville], and Early, since he was three miles east of Heidlersburg, was ordered to go south to Hunterstown on a road parallel to the Harrisburg Pike and then turn west toward Mummasburg and Cashtown. By going to Hunterstown, which was a little more than half the distance from Heidlersburg to Gettysburg, Early could come within four miles of Gettysburg before turning west for Cashtown. Should `circumstances dictate’ he could proceed to Gettysburg without a hitch.”
Coddington, Edwin B., The Gettysburg Campaign, A Study in Command, Touchstone Press, New York, 1997. ISBN 0-684-84569-5
So, with Ewell [minus Johnson's Division] at Heidlersburg and moving south toward Gettysburg and Cashtown, and Hill at Cashtown, why would Lee fear Heth getting involved heavily at Gettysburg?
It could not have been because he wanted more than one division to start things, since there were four other divisions close at hand, two of which were actually moving toward Gettysburg.
I have an idea about this, but I would love to see what others have to say first…