A deceptively simple mixture, ferrous sulfate (FeSO4), hydrogen peroxide (H2O2), tartaric acid (C4H6O6), and water (H2O), initiated a century-long argument and a convoluted hunt to understand the oxidation mechanism(s) initiated by the combination of these components. Fenton’s discovery rallied a legion of scientists, including two Nobel Winners, to find an explanation for the chemistry discovered when a graduate student mixed a couple of random chemicals, producing a molecule that became purple in strong base. Those investigation uncovered three separate branches of iron/oxygen chemistry, the Hydroxyl Radical [HO•], the Ferryl-Oxo Ion [Fe = O]+2, and the Perferryl-Oxo Ion [Fe = O]+3. Today their uses include chemical modifications [either untargeted and random [HO•] or targeted and selective [Fe = O]+2, [Fe = O]+3 dehydrogenations and/or oxygen additions] to effective and green oxidation and mineralization of persistent organic wastes.