I don't exactly have a poem to go off of here, but what happened was that Paul Revere saw the signal lanterns under Christ church and night. This was a signal that the British were there and ready for war. Then he got on his horse, and went all through town screaming "The British Are Coming!" which woke everyone up, and they saw the lantern as well. Paul's warning gave the colonists and the militia men time to prepare for the fight. Basically saving them.
