From early times kites have been more than toys. They have had many practical uses. Some uses were military. About 500 A.D. one Chinese emperor used kites to signal his soldiers. The soldiers would work on nearby farms until they saw the kites flying above the emperor's palace. This was a signal that they should rush to the palace to help defend it against enemies seen approaching on the horizon.
During the American Civil War in the 1860's, the Union used
kites to scatter leaflets over Confederate troops. The leaflets urged the
Confederates to surrender, promising them amnesty if they would lay down their
arms. During the Boer War in South Africa in the late 1890's, large kites were
used to carry British soldiers over the fighting front to observe the enemy.
During World Wars I and II, kites were used to disable enemy aircraft. (Grolier Book of Knowledge Encyclopedia)