Patriot's Day commemorates the revolutionary Battles of Lexington and Concord on April 17th. It is not a federal holiday but rather a state holiday here in Massachusetts and Maine. (Maine was once a district of Massachusetts)
We learned in American history that this was the first conflict of the revolution and that the gunfire was known as "the shot that was heard around the world," a line taken from Ralph Waldo Emerson's poem, "Concord Hymn." It may not have been the first conflict but it certainly it was the first one with multiple and fatal causalities.
But on Sunday, February 26, 1775 another conflict was in progress. By then the colonists where already having "illegal" town meetings and stockpiling weapons and ammunition against the King's orders. On February 7th the military governor of Massachusetts, a General Thomas Gage declared the commonwealth to be in a high state of rebellion.
The people of Salem had acquired several cannon from a local military hero, a Colonel Pickering, of the French and Indian War. The British General, ordered a Colonel Alexander Leslie to capture these cannon.
On Saturday night they secretly sailed from Boston to Marblehead Neck. The next morning the King's "regulars" stayed below deck until they thought that the colonists were in church. The Sabbath day was a day of rest and worship and it was taken literally by the the Puritans. Church was an all day affair. When the King's "regulars" were confident they wouldn't be spotted they began to come ashore.
Once Commander Pedrick of the Marblehead Militia caught wind of what was going on he ordered church bells to be rung and rode to neighboring Salem to warn the citizens there. His ride was known widely as a "powder alarm." These alarms were basically a way to warn people of movements of the British troops. Paul Revere's ride to Lexington was one of these powder alarms.
When the troops marched into Salem, the cannons had already been moved and hidden under leaves in the woods of nearby Danvers. The North River bridge was raised to prevent them from marching further. When it appeared as though the troops would commandeer local boats to cross, the colonists used hatchets to scuttle them.
Colonel Leslie and his troops where getting agitated from the colonists taunting just across the river. Both sides tried to negotiate an agreement mediated by the local minister. In the process there was a scuffle and one colonist was injured by the point of a regular's bayonet.
Finally an agreement was made. The colonists would lower the bridge. In exchange the British troops would march only 20 rods further, not search for the cannons, then return to their ship.
This obscure event in American history is now known as Leslie's Retreat and is honored by a simple bronze plaque at the site of the original North River Bridge.