The night before the battle at Lexington, the town militia met on the Lexington common to wait for British troops. They eventually moved into this tavern, which was a popular stopping place after training exercises. Militia members were given free beer to encourage them to show up, because freedom fighters are at their sharpest and best after six pints and a packet of nuts.
Just before dawn the soldiers went back onto the common to meet the British forces. No one knows who fired the first shot, but some accounts say it came from "the corner of a house to the right of the church" - namely, Buckman tavern. Classic pub fight.