As British troops retreated to Boston after the battles of Lexington and Concord, they encountered fierce resistance from colonial militias, who employed snipers and ambush tactics.

The militias, leveraging their familiarity with the local landscape, executed surprise assaults from behind trees and fences, complicating the British forces' ability to regroup or hold their formation. This persistent harassment resulted in considerable losses for the retreating troops, with estimates indicating that more than 270 British soldiers were killed. The retreat highlighted the determination and tenacity of the colonial fighters, intensifying the conflict's tensions.