Smith meant the scene of the fighting, not the Pry House. Smith reached Sumner before 1000 and started formingd his division into mass (i.e. columns). Immediately news came that the rebels who had pursued Sedgwick were close to overrunning the artillery, and Smith sent Hancock forward. Notably, Smith placed the charge of the 7th Maine here, whereas ISTR Carman (and those that used his example) moved it to the late afternoon.
As Siciliano puts it:
"The next day, McClellan ordered Franklin's corps to join the
rest of the army before Sharpsburg. The corps left their encampment in
the rear of Rohrersville, in Pleasant Valley, at 5:30 in the morning
of September 17. Smith's division led the column, and its head arrived
at the field of battle about 10:00. Sumner, the commander of the Union
right, ordered Baldy to form his division closed in mass facing to the
northeast. Just as the leading brigade, the First Brigade, had been
placed, Colonel J. Taylor, Sumner's Adjutant-General, came galloping
up to Smith and said: "The enemy's skirmishers are advancing from
the front, and if you don't get some troops out there immediately,
our artillery will be captured." Without referring the matter to
Sumner, Smith directed Hancock to deploy his force under Taylor's
guidance. Hancock's brigade drove away the Confederate skirmishers,
who had advanced close to the batteries. Hancock detached some companies
to occupy some buildings and fences in front of his position. The
Confederates moved up two batteries and opened fire on Hancock's position.
Despite severe enemy artillery fire, Hancock's skirmishers and artillery
silenced the Confederate batteries and forced their withdrawal with
the loss of several limbers. The First Brigade assisted in saving two
batteries and held its position during the remainder of the action,
sometimes under very heavy artillery fire.'
The next brigade to arrive was Smith's Third Brigade under
Irwin. Smith formed up the brigade and ordered it forward to meet the
approaching enemy. The brigade, animated by the words and examples
of Smith and its own officers, dashed at the enemy and was soon hotly
engaged with them. The Confederates could not endure the brigade charge
and broke in confusion. They drove the Confederates to the little
church at the edge of the woods, but at this point a severe flank fire
from the woods on the right threw the Thirty-Third and Seventy-Seventh
New York slightly into confusion. Smith riding along the line and
discovering the advanced and unprotected position of the two regiments,
sent an aide to order them to retire. They closed up, faced by the rear
rank, and poured in a close and scorching fire, driving back and
scattering the enemy. The men were then ordered to lie down behind the
crest of a slope facing the woods and open ground to its right. The
rest of the brigade was ordered to face to their proper front and
form behind a crest nearly at right angles to the other. 148
With Irwin being heavily engaged, Smith sent back for Brooks'
brigade to support Irwin. Smith intended to place Brooks on Irwin's
left in front of the Hagerstown turnpike. In this position, Brooks'
right could also take advantage of the crest which shielded Irwin's
brigade. Without Smith's knowledge or consent, however, Sumner ordered
Brooks' brigade to reinforce General French's brigade which had nearly
expended its ammunition. On reaching French's right, Brooks found
that the enemy had been checked and repelled. The brigade then occupied
a position on French's right, which situated it on Irwin's left.
Brooks stayed there for the remainder of the day and night, frequently
coming under enemy artillery fire. Smith later complained in his report
about this detachment of Brooks' brigade: "It is not the first or
second time during a battle that my command has been dispersed by
orders from an officer superior in rank to the general commanding
this corps, and I must assert that I have never known any good to arise
from such a method of fighting a battle, and think the contrary rule
should be adopted of keeping commands intact." 149
By this time, Franklin had come up and Smith reported his
movements and position to him. After talking matters over, the two
generals agreed that they could make an assault on the Confederate left
without repeating the tactical blunders made in the previous assaults.
Franklin went to Sumner and told him his plans, but Sumner disapproved
them since the repulse of the Sixth Corps would imperil the safety of
the army."