In 1948, Chesterfield showed that it was the favorite choice of "professional smokers". "They smell milder!"
Bing Crosby invites Lauren Bacall and then Humphrey Bogart to pitch Chesterfield (I think around 1950).
In 1953 Chesterfield conclusively proves that smoking is not bad for you. "It comes from a doctor!"
Here Chesterfield gloms on to to the success Marlboro had inventing the cowboy as the ultimate in lung-killing manliness.