Explain the spy system that paul Revere organized?

Paul Revere starts a spy network as promised, and it expands quickly. Johnny is assigned to spy on Colonel Smith and the other officers who live at the Afric Queen. Revere emphasizes that Johnny must stay close to Dove, who might have information if Colonel Smith is planning an action against the rebels. With the help of Lydia, Johnny discovers a shredded note that Colonel Smith wrote to Lavinia Lyte, who he is courting. Together with Rab and Uncle Lorne, Johnny puts the note back together and figures out that Colonel Smith is going to be part of a large raid on Portsmouth, sixty miles north.

Johnny rushes off to warn Paul Revere about the raid. Revere rides the sixty miles to Portsmouth himself and warns the rebels that the British are coming. They seize the fort in Portsmouth before the British reinforcements can arrive.