Today, spies often use satellites to take pictures of enemy territory. But back in World Wars I and II, they didn't have satellites. Instead, they used pigeons! Specially trained birds were used for these missions. A tiny camera was strapped around a spy pigeon. The bird would fly over enemy areas. Then it would fly home to deliver the film! The birds were also used to deliver secret messages. This was especially useful in areas where it would be dangerous for a person to travel on land.