The Robber Baron was John D. Rockefeller. The
journalist and writer Ida Tarbell, in her book The History of the
Standard Oil Company, publicly exposed in 1904, all the ruthless
strategies and ways in which John D. Rockefeller, achieved that his
company, Standard Oil became the largest monopoly of the world (at that time). Ida
Tarbell's book inspired Americans to change their way of seeing the
economy, and fight against monopolies, like Rockefeller's.