Little Georgie Gobel was a star on radio, until his singing career was interrupted by WWII. While in the service, he started doing stand-up for his fellow soldiers, which started him on a new career path. In 1954, he landed on NBC, doing The George Gobel show, for which he received an Emmy.
CBS needed to counter George Gobel, and in 1955, they introduced Johnny Carson's series. He was from radio, and from the Midwest, just like Gobel, but offered a more sophisticated personality as opposed to Gobel's "aw shucks" down home style.
Gobel ended up moving to CBS and Carson to NBC. CBS ended up fighting a demographic war for decades, with a large audience, but one of older, rural viewers that advertisers found less desirable.
The Tonight Show formula that Carson used was basically this half-hour show, plus interviews with celebrities and authors.
Carson protégé and heir-apparent David Letterman ended up moving to CBS when NBC chose Jay Leno to replace the retiring Carson, thus completing the circle back to CBS.
