“As concerns about the health implications of smoking persisted — and then increased — in the 1930s and 1940s, advertising explicitly addressed these anxieties…. R. J. Reynolds fixed on the likely notion that smokers would be attracted to the brand that their physician chose, and that physicians would advocate for a brand that lionized the medical profession….
“The ‘More Doctors Smoke Camels’ campaign was apparently based on the work of A. Grant Clarke, a William Esty ad executive, on loan to R. J. Reynolds to establish a Medical Relations Division. Clarke would distributed free packs of Camels at medical conventions; pollsters from an ‘independent research organization’ would then be sent to ask the physicians what brand of cigarettes they were carrying.”
— From “The Cigarette Century: The Rise, Fall and Deadly Persistence of the Product that Defined America” (2007) by Allan M. Brandt