Hailing from relatively modest beginnings, John D. Rockefeller managed to become one of the wealthiest Americans, if not the wealthiest of all times. His rise started with his first partnership which began supplying food to the Union Army. He next got into oil which was starting to be refined into kerosene which was mainly used as a replacement for whale oil which was becoming too expensive for lighting.
While there were multiple innovations such as selling all the oil byproducts, Rockefeller became extremely successful because of his ruthless business practices which included buying up unsuccessful refiners, and negotiating discounts and rebates on freight with the railroads. While it did bring the price of kerosene down,