It was during this time that he was involved in a number of building designs including the current Embassy of Ireland in Washington.

[2] Cresson's diplomatic career began in 1909 when he was appointed Secretary to the American Legation in Lima, Peru.

[2] During World War I – Cresson was commissioned as Lieutenant in the Aviation Section of the U.S Signal Corp's reserve component and was subsequently promoted to captain.

During this time he was decorated a Chevalier of the Order of Leopold and received the Croix de Guerre.

[3] When the war ended, he continued his service as a Major in the Reserve Officer's Training Corps – as well as accepting a post as Assistant Professor of International Law in Princeton University.