On hearing of the British approach, Parker gave his drummer orders to beat assembly. Shortly after, the lead company of Smith’s column spotted Parker’s troops on the Green and angled right along the Bedford Road, while British Maj. John Pitcairn spurred his horse left around the church to get a better view. British officers and Massachusetts militia arrived on the green separated from each other.
When Pitcairn reunited with his soldiers, he found that several companies of his light infantry had formed into line and were facing off against Parker’s militia. He and the other officers with him began to issue contradictory commands to Parker, both to “disperse” and “surrender.” Confusion reigned.
"When I arrived at the end of the village, I observed drawn up upon a green near 200 of the rebels; when I came within one hundred yards of them, they began to file off toward some stone walls on our right flank—the light infantry, observing this, ran after them"
Maj. John PitcairnMaj. John Pitcairn to Lt. Gen. Thomas Gage, letter report dated Boston, April 26, 1775, Thomas Gage Papers, William L. Clements Library, The University of Michigan.