Because very few people had a television.
1939
NO! Radio was in use well before world war 1!!!!
by radio
Radio
Radio operator !
was it Neville chainberlain
There was one radio operator per bomber plane in the airforce planes. This one was easy. My father was a radio operator in the 8th Air Force in World War 2.
They did not have TVs in world war 2 but they did use the radio
Radio Direction Finder
Newspapers and radio
the radio.
Newspapers and radio announcements