The United States Army Pigeon Service (a.k.a. Signal Pigeon Corps) was a unit of the United States Army during World War I and World War II. Their assignment was the training and usage of homing pigeons for communication and reconnaissance purposes. During World War II, the force consisted of 3,150 soldiers and 54,000 war pigeons, which were considered an undetectable method of communication. Over 90% of US Army messages sent by pigeons were received.