Banu's career in politics reached the international level during World War I, when he took refuge from German-occupied Romania to campaign for the Romanian cause in Paris. Subsequently, during his term as minister, he focused on negotiating a Romanian Concordat and normalizing relations with the Catholic Church. In his final years in politics, he was an affiliate of the National Liberal Party-Brătianu. These activities, like much of his vast (but fragmentary) work in print, or his speeches, endured as the focus of political controversy.