The role for which he is most remembered today was as a night-time messenger on horseback just before the battles of Lexington and Concord. His famous "Midnight Ride" occurred on the night of April 18/April 19, 1775, when he and William Dawes were instructed by Dr. Joseph Warren to ride from Boston to Lexington to warn John Hancock and Samuel Adams of the movements of the British Army, which was beginning a march from Boston to Lexington, ostensibly to arrest Hancock and Adams and seize the weapons stores in Concord.
The British army (the King's "regulars") had been stationed in Boston since the ports were closed in the wake of the Boston Tea Party, and was under constant surveillance by Revere and other patriots as word began to spread that they were planning a move. On the night of April 18, 1775, the army began its move across the Charles River toward Lexington, and the Sons of Liberty immediately went into action. At about 11 pm, Revere was sent by Dr. Warren across the Charles River to Charlestown, on the opposite shore, where he could begin a ride to Lexington, while Dawes was sent the long way around, via the Boston Neck and the land route to Lexington.
In the days before April 18, Revere had instructed Robert Newman, the sexton of the Old North Church, to send a signal by lantern to alert colonists in Charlestown as to the movements of the troops when the information became known. One lantern in the steeple would signal the army's choice of the land route, while two lanterns would signal the route "by water" across the Charles River. This was done to get the message through to Charlestown in the event that both Revere and Dawes were captured. Newman and Captain John Pulling momentarily held two lanterns in the Old North Church as Revere himself set out on his ride, to indicate that the British soldiers were in fact crossing the Charles River that night. Revere rode a horse lent to him by John Larkin, Deacon of the Old North Church.