The Confederates opened a rapid artillery fire from the open ground in front of the Dunker Church as well as from Stuart's position, and Hooker answered the challenge by an immediate order for his line to advance. Doubleday directed Gibbon, who was on the right, to guide upon the turnpike. Patrick remained for a time in the wood north of the Miller house, till he should be needed at the front. [Footnote: Official Records, vol. xix. pt. i. p. 224.] Doubleday and his brigade commanders seem to have supposed that Meade's men occupied part at least of the West Wood, and that they would cover Gibbon's flank as he advanced. This belief was based on the stationing of the Tenth Pennsylvania Reserves; but that regiment was fifteen or twenty rods north of the northern end of the West Wood, and Gibbon's right flank, as he advanced, was soon exposed to attack from Ewell's division (Lawton in command), which held the wood, hidden from view and perfectly protected by the slope of the ground and the forest, as they looked over the rim into the undulating open fields in front. Part of Battery B, Fourth United States Artillery (Gibbon's own battery), was run forward to Miller's barn and stack-yard on the right of the road, and fired over the heads of the advancing regiments. [Footnote: _Id_., pp. 229, 248.] Other batteries were similarly placed, more to the left, and our cannon roared from all the hill crests encircling the field. The line moved swiftly forward through Miller's orchard and kitchen garden, breaking through a stout picket fence on the near side, down into the moist ground of the hollow, and up through the corn which was higher than their heads and shut out everything from view. [Footnote: Dawes, Sixth Wisconsin, p. 88.] At the southern side of the field they came to a low fence, beyond which was the open field already mentioned, and the enemy's line at the further side of it. But the cornfield only covered part of the line, and Gibbon's right had outmarched the left, which had been exposed to a terrible fire. The direction taken had been a little oblique, so that the right wing of the Sixth Wisconsin (the flanking regiment) had crossed the turnpike and was suddenly assailed by a sharp fire from the West Wood on its flank. They swung back into the road, lying down along the high, stout post-and-rail fence, keeping up their fire by shooting between the rails. [Footnote: Dawes, Sixth Wisconsin, p. 89.]