Militia companies were mustering but their members, like those in Lexington, were intent on not being the first to open hostilities. From this spot, Colonel James Barrett saw his companies returning, followed by the British, and made the decision to pull back across the North Bridge.
With no idea of what had happened in Lexington, and still heavily outnumbered, Col. Barrett resolved to leave Concord to the British and hold the high ground west of town.
"we were then formed, the minute (men) on the right, & Capt. Barrett's (militia company) on the left, & marched in order to the end of Meriam's hill then so called & saw the British troops a coming down Brooks Hill. The sun was arising & shined on their arms & they made a noble appearance in their red coats & glistening arms""
Pvt. Thaddeus Blood, Capt. Nathan Barrett’s Concord Militia Company“April 19, 1775,” National Park Service, https://www.nps.gov/mima/learn/historyculture/april-19-1775.htm