In 1941 – 80% of US AM radio frequencies were reassigned to new channels as part of the North American Radio Broadcasting Agreement.
In 1945 – German soldiers blew the launch tracks for the V-1 rocket site near Letelle, Netherlands, ending the rocket attacks.
In 1974 – NASA’s Mariner 10 became the first spaceprobe to cross the orbit of Mercury about 704 km from the surface.