 However, before the investigation of his activities had progressed beyond the questioning of his students, the archbishop and his court fled from the advancing French troops under General Custine, who arrived in Mainz on 21 October 1792.Two days later, Hofmann helped found the Mainz Jacobin club and became one of its most active members.A popular and powerful orator, he criticised both the old regime of the Elector and the French military government in his speeches, which were especially supported by the more radical students who idolised the incorruptible Hofmann.