When Arnold was eleven, his father responded to the Spanish–American War by serving as a surgeon in the Pennsylvania National Guard, of which he remained a member for the next 24 years.
== Življenjepis ===== Zgodnje življenje in kariera ===Rojen je bil 25. junija 1886 v Gladwynu (Pensilvanija) v družini zdravnika Herberta A. Arnolda, člana vplivne politične in vojaške rodbine Arnold.