Irwin began his writing career as a humorist with the San Francisco magazine The Lark but quickly moved on to war reporting and nonfiction writing on serious subjects. Managing editor, McClure's Magazine, 1906-07; writer, Collier's Weekly, 1907-08; war correspondent for the London Daily Mail 1914-15, and the Saturday Evening Post, 1916-18. His brother was humorist Wallace Irwin and his wife was reporter-novelist Inez Haynes Irwin.
