I thought the war on drugs started in earnest in the 80's and 90's in response to a growing crime wave. My (uneducated) belief was that it was championed by the inner city churches in an effort to clean up their neighborhoods.
see eg: 1969. December 3. President Richard Nixon convenes a gathering of nation’s governors to talk about drug crisis. Says that part of the solution must be treatment and rehabilitation.
“When you’re talking about thirteen year olds and fourteen year olds and fifteen year olds, the answer is not more penalties. The answer is information. The answer is understanding,” Nixon says.
According to CBS News, Nixon administration is considering reduced penalties for marijuana possession, along with more education, in an effort to convince young people to avoid “experimenting with still stronger drugs.”
http://prisontime.org/2013/08/12/timeline-black-support-for-...
and
Rep. Charles Rangel, a newly-elected Democrat from New York City and a former Federal prosecutor, urges Nixon to do more to fight drugs without waiting for further congressional action, warning that support might soon build for drug legalization.
“You do have the power and we implore you to use it as you would if this were a national crisis and I think we’ve reached that,” Rangel insists.
Before departing, the Black Caucus presented Nixon with a manifesto of sixty priorities for the African American community. It included the demand that “drug abuse and addiction be declared a major national crisis” and a call to use “all existing resources” to stop the trafficking of drugs. http://prisontime.org/2013/08/12/timeline-black-support-for-...