TERCOM: How a Missile Navigates Before GPS
Since GPS satellites had not been invented yet, this unmanned vehicle needed to have a way to navigate to target accurately. This was accomplished by two systems which would operate at different time,s with an inertial guidance system operating while the vehicle was at it's cruise speed, 35,000 feet in the air, followed by what would eventually be called TERCOM, or Terrain Contour Matching, and used in USAF cruise missiles such as the tomahawk to this day. The system compared radar images of features on the ground to a prerecorded list of possible landmarks in it's memory, based on it's flight path. it would compare it's radar returns with this internal memory, and guide itself to targets. It is succinctly, if hilariously, described in this video, which utilizes audio from an official training film: