O'Brien was influenced by the socialist writer, Gracchus Babeuf, who had been executed during the French Revolution. In 1836 O'Brien began publishing translations of Babeuf's work in the Poor Man's Guardian. He also included Filippo Buonarroti's account of Babeuf and the Conspiracy of Equals. O'Brien became fascinated with the history of radicalism and began work on books on Robespierre, the French Revolution and the English Commonwealth. However, the authorities raided his house in 1838 and seized his manuscripts and the projects were never completed.