Date: April 18–19, 1775
On the night before the Battles of Lexington and Concord, Paul Revere and William Dawes left Boston to warn the countryside that the British Regulars were on the march. In particular, they wanted to warn John Hancock and Samuel Adams that the Regulars intended to arrest them.
Revere left Boston by boat across the Charles River, taking the road across the Charlestown peninsula. Dawes took the longer land route across Boston Neck. Revere arrived in Lexington first, but Dawes wasn't far behind.
Once they'd delivered their warning to Hancock and Adams in Lexington, Dawes and Revere decided to continue to Concord to warn people there of the coming raid. They joined up with Samuel Prescott, who was visiting his fiancée in Lexington. Prescott lived in Concord, and so knew the area well. Road trip!
The three men were halfway to Concord when they were stopped by a British patrol. Revere was captured, but Dawes and Prescott broke away. Dawes lost his horse and hid in a barn for several hours before sneaking back to Lexington, but Prescott reached Concord to sound the alarm. (Good things they had him tag along).
Years later, Henry Wadsworth Longfellow would write a poem about the event, which rolled all of the riders into one - Paul Revere. Which is why everyone knows his name - and why Revere is so revered.