D'Olier was one of the original 20 men who initiated The American Legion in France, February 15, 1919, and attended the Paris caucus of The American Legion on March 15, 1919. After his discharge from the service, D'Olier joined
Theodore Roosevelt Jr., who was at that time—early in 1919—perfecting the preliminary organization of The American Legion in the
United States preparatory to the
St. Louis caucus, May 8, 9 and 10. He was chairman of the
Pennsylvania delegation at the St. Louis Caucus and a member of the National Executive Committee from Pennsylvania. In 1944 in answer to a request by
Secretary of War Stimson, D'Olier organized and directed the
United States Strategic Bombing Survey. This group of observers and technicians worked in both the
European and
Pacific theaters of war gathering data on the effectiveness of
air bombardment "upon the will and capacity of the enemy to resist." Among the recommendations made in the report of the mission were those asking for a separate
Air Force and creation of a
Department of Defense. In 1946 D'Olier became chairman of the board of directors of Prudential and continued to serve actively as a director of the company until his death. He was also a director of the Howard Savings Institution of Newark, New Jersey;
National Biscuit Company;
Pennsylvania Railroad; General Refractories Company;
American Enka Corporation and the Morristown Trust Company. At various times he had been called upon to serve as chairman of the New Jersey committee of the
U. S. Treasury War Finance Committee; state chairman of the
USO;
Civilian Defense director of the 2d
Corps area and as a member of the New Jersey State Economic Commission. He was a life trustee of Princeton university. He died on December 10, 1953, in
Morristown, New Jersey, a year after the birth of his great-grandson
Christopher Reeve. == Military awards ==