It was on tis date in 1775 that the first battles of the American rebellion began in Middlesex County, Province of Massachusetts Bay, within the towns of Lexington, Concord, Lincoln, Menotomy (present-day Arlington), and Cambridge, near Boston. The battles marked the outbreak of open armed conflict between the Kingdom of Great Britain and its thirteen colonies in the mainland of British North America.
About 700 British Army regulars, under Lieutenant Colonel Francis Smith, were given secret orders to capture and destroy military supplies that were reportedly stored by the Massachusetts militia at Concord. Through effective intelligence gathering, Patriot colonials had received word weeks before the expedition that their supplies might be at risk and had moved most of them to other locations. They also received details about British plans on the night before the battle and were able to rapidly notify the area militias of the enemy movement.
The first shots were fired just as the sun was rising at Lexington. The militia were outnumbered and fell back, and the regulars proceeded on to Concord, where they searched for the supplies. At the North Bridge in Concord, approximately 500 militiamen fought and defeated three companies of the King's troops. The outnumbered regulars fell back from the minutemen after a pitched battle in open territory.
More militiamen arrived soon thereafter and inflicted heavy damage on the regulars as they marched back towards Boston. Upon returning to Lexington, Smith's expedition was rescued by reinforcements under Brigadier General Hugh Percy. The combined force, now of about 1,700 men, marched back to Boston under heavy fire in a tactical withdrawal and eventually reached the safety of Charlestown. The accumulated militias then blockaded the narrow land accesses to Charlestown and Boston, starting the Siege of Boston.