Hackworth quickly developed a reputation as an eccentric but effective soldier, becoming a public figure in several books authored by General S. L. A. "Slam" Marshall. Following a stateside tour at the Pentagon and promotion to lieutenant colonel, Hackworth co-wrote "The Vietnam Primer" with Marshall after returning to Vietnam in the winter of 1966–67 on an Army-sponsored tour with the famous historian and commentator. The book advised counter-insurgency fighters to adopt some of the guerrilla tactics used by Mao Zedong, Che Guevara, and Ho Chi Minh. Hackworth described the strategy as "out-G-ing the G." His personal and professional relationship with Marshall soured as Hackworth became suspicious of his methods and motivation.