As we may recall the story behind Paul Revere and his infamous horse ride through town, many of us also know the battle of Lexington and Concorde was the first open battle of the Revolutionary War. So when is Patriots' Day? It is today, April 19. Although April 19 is the anniversary of Patriots' Day it is celebrated on the third Monday of April which in our case this year also happens to be today. We celebrate this holiday with the traditional Boston Marathon, and also the Boston Redsox will typically also play a home game! Now you know those two sporting events actually have significance to their dates.