What was Johhny’s role in giving the message to the minutemen?

Johnny is sent to tell Robert Newman, the church sexton, to put two lanterns in the spire of Christ’s Church, and to spy on the ships in the mouth of the Charles. Johnny performs these tasks admirably, pretending to be a young child to get past the British patrol officers. Paul Revere and Dr. Warren say good-bye to each other. Although they are stoic, it is obvious that the two friends may never see each other again.