Depends what you call "the field" doesn't it. As you should know from our previous conversations, the orders were all verbal since they were running out of paper and hence little is recorded. Indeed, this lack of paper contributed to
Hammerstein failing to deliver an order from McClellan to Wessells. I should maybe just repeat myself:
When McClellan left the Dew House after receiving Rodger's note at 1600 there was no attack, merely some exchange of artillery fire. Longstreet ordered Jenkins to advance skirmishers to snipe the gunners, but around 1630 Jenkins took his brigade and charged the Federal batteries from the front. Wilcox thought they were attacking and launched his two ready regiments as well. With an ad hoc attack underway Longstreet orders Kemper and Branch to attack at 1700. Kemper launches 1715-30, but Branch's brigade (the one nearest McClellan's CP at the Dew House) had gone into routine and were around their cooking fires; they didn't launch until around 1800. Other "attacks" were launched after 1830, but were essentially demonstrations to cover breaking contact.
McClellan is down at Haxalls when Jenkins launches, and is on the Galena or on a boat back from the Galena when Kemper launches. By the time Branch launches he is ashore and probably riding up Malvern Hill. He would be back at his CP before AP Hill launched any attacks.
Let me also note that the column under Holmes that attacked Malvern was Lee's main effort, and we know this because this is where he sent his reserve force (Magruder). The force at the crossroads was merely making a demonstration against the centre to stop McClellan pulling forces from there onto Malvern Hill. Jenkins' unordered attack indeed caused McClellan to react as Lee wanted, he sent forces from Malvern Hill to the crossroads, but Holmes' attack was smothered by artillery and the gunboats and was defeated easily.
McClellan's signals after he was informed of the attack at the crossroads certainly include orders for reserves to reinforce the centre, as Couch is explicit where the order came from. The question of who ordered the 4 brigades from White Oak is unresolved, and quite possibly everyone did. The two from Sedgwick's brigade we know were en route before the attack, and also received orders from multiple staff officers from various commanders to hurry up. The two brigades from Richardson's division were not ordered to move until after 1800. Meagher had been at Sumner's HQ for a while asking for Sumner to order them to the contact, and after 1800 Sumner did. We have no information about whether Sumner suddenly changed his mind or whether he received orders to that effect we don't know either way.
Essentially of the seven brigades that moved (or should have) to the New Market crossroads:
* Two (Dana and Sully) were ordered there well before McClellan left for the Galena, but had been sent over to counter a threat by Huger en route and then proceeded to the crossroads.
* Two (Howe and Palmer) were absolutely verifiably ordered there by McClellan, with Maj Webb carrying the order.
* Two (Caldwell and Meagher) were ordered there around 1800 hrs by Sumner under unknown circumstances.
* One (Wessells) was ordered to the crossroads by McClellan but the aide carrying the order (Hammerstein) could not find them and so headed on with his other orders
The order to Howe and Palmer was carried from the signals station by Maj Webb. The order to move Wessells was carried by Maj Hammerstein, who stated he could not spend long looking for him as he "had to move other troops". Which other troops were these? The only other significant troop movement on the field in the hour after this was that of Meagher and Caldwell, and the obvious answer is that he was tasked to move reinforcements down from White Oak Swamp to New Market Crossroads, unless you know of another troop movement?