The historic midnight ride of Paul Revere is set to be reenacted Monday but with some modern-day tweaks: It will be run in the middle of the day, and the horse and rider will have a police escort. The ride is celebrating its 251st anniversary. It is considered a critical moment in the early days of the American Revolution. Revere rowed across the river to Charlestown the evening of April 18, 1775, and then set out for Lexington. He arrived around midnight to warn Samuel Adams and John Hancock of the impending British raid on Concord military stockpiles. A separate rider, William Dawes, reached Lexington soon after with the same message.