In 1920’s, pilotless aircraft were tested by the Army and these were called “Bugs”. These machines were controlled by electrical and vacuum-pneumatic controls. After some time, the aircraft automatically turned itself off and would fall to the ground. It was a very heavy vehicle – weighing up to 80 kg and wherever it fell, it was considered an enemy target. Today’s guided missiles can be traced back to this forerunner that was discontinued around the end of 1920’s.
A couple of decades later anti-aircraft target practice came into being and for this pilotless planes were used. Much later, USA started using drones that were not very technically advanced for the purpose of electronic intelligence gathering, reconnaissance, and surveillance.