Complex sentence: The 664th AC&WS and similar military units were eventually superseded by the North American Aerospace Defense Command (or NORAD), and the base in Bellefontaine was closed in 1969.
Split into simpler sentences: The 664th AC&WS and similar military units were eventually superseded by the North American Aerospace Defense Command (or NORAD). The base in Bellefontaine was closed in 1969.