This is from the "horse's mouth" in his article in 2 B&L:
[p. 409]
"Our new field of battle embraced Malvern Hill, just north of Turkey Creek and Crew's Hill, about one mile farther north. Both hills have given name to the interesting and eventful battle which took place on July 1st, and which I shall now attempt to describe.
The forces which on this occasion came under my control, and were engaged in or held ready to enter the contest, were my own corps, consisting of Morell's, Sykes's and McCall's divisions, Colonel H. J. Hunt's Artillery Reserve of one hundred pieces, including Colonel R. 0. Tyler's Connecticut siege artillery, Couch's division of Keyes's corps, the brigades of John C. Caldwell and Thomas F. Meagher of Sumner's corps, and the brigade of D. E. Sickles of Heintzelman's corps. Though Couch was placed under my command, he was left uncontrolled by me, as will be seen hereafter. The other brigades were sent to me by their respective division commanders, in anticipation of my needs or at my request.
…
[p. 414]
General McClellan, accompanied by his staff, visited our lines at an early hour, and approved my measures and those of General Couch, or changed them where it was deemed advisable. Though he left me in charge of that part of the field occupied by Couch, I at no time undertook to control that general, or even indicated a desire to do so, but with full confidence in his ability, which was justified by the result of his action, left him free to act in accordance with his own judgment.
…
[p. 416]
While the enemy's artillery was firing upon us General Sumner withdrew part of his corps to the slope of Malvern Hill, to the right of the Malvern house, which descended into the valley of Western Run. Then, deeming it advisable to withdraw all our troops to that line, he ordered me to fall back to the Malvern house; but I protested that such a movement would be disastrous, and declined to obey the order until I could confer with General McClellan, who had approved of the disposition of our troops.
…
[p. 421]
It was at this time, in answer to my call for aid, that Sumner sent me Meagher, and Heintzelman sent Sickles, both of whom reached me in the height of battle, when, if ever, fresh troops would renew our confidence and insure our success.
…
[p. 423]
I received orders from him to withdraw, and to direct Generals Sumner and Heintzelman to move at specified hours to Harrison's Landing and General Couch to rejoin his corps, which was then under way to the same point. FN …
FN "The General Commanding desires you to move your command at once, the artillery reserve moving first to Harrison's Bar. In case you should find it impossible to move your heavy artillery, you are to spike the guns and destroy the carriages. Couch's command will move under your orders. Communicate these instructions to him at once. The corps of Heintzelman and Sumner we move next. Please communicate to General Heintzelman the time of your moving. …"