What happened during the Battles of Lexington and Concord?

The Battles of Lexington and Concord were notable for being the first military engagements of the Revolutionary War. It all started on the night of April 18th, 1775, when a large detachment of British soldiers marched from Boston to Concord to get their hands on an arms cache, which was believed to be able to disrupt public order. A group of Minutemen under the leadership of Paul Revere attempted to intercept the British troops at Lexington, and a brief skirmish ensued after the rebels refused to put down their weapons. To this day, no one knows exactly who fired the first shots, but whoever it was officially started off the hostilities between the American colonists and the British.
The British continued on to Concord, and once there, they began to search for weapons. Most of them had already been moved elsewhere, and the British burned the few that remained. The fire soon got out of hand, leading patriot militiamen to believe that the British were going to torch the entire town. Over two thousand militiamen descended on the town, and a full-scale battle broke out.
After fierce fighting, the British retreated to Lexington, where yet more fighting took place. A newly-arrived column of militiamen had the chance to cut off the British and finish them off for good, but their commander ordered them to hold back, so the Redcoats were able to beat a retreat to Charlestown Neck, where they could count on naval support.
Over the course of that incredible day, the patriots took the fight to the British, and although their marksmanship was less than accurate, the very fact that they went toe-to-toe with the world's strongest army was significant and hinted at what was to come.