 After interviewing McIlwain personally, Wilson appointed him to the inaugural group of 45 Princeton preceptors.McIlwain remained at Princeton until 1910, when he left to become the Thomas Brackett Reed Professor of History and Political Science at Bowdoin College.There he published his first book, "The High Court of Parliament and Its Supremacy", which caught the attention of fellow historians and led to his appointment in 1911 as an assistant professor of history at Harvard.