Date When Celebrated: Third Monday in April Some people know little or nothing about Patriot's Day. To New Englander's, it is a big, big day. In the states in New England, it's a holiday with a day off of work. Banks, schools, post offices, and businesses have the day off. Patriot's Day commemorates the Battle of Lexington and Concord on April 19, 1775. This battle began the American Revolutionary War. It also honors the "Midnight Ride of Paul Revere", that evening when Paul Revere rode through town warning the colonists that "The Red Coats are coming!"