Captain Puleston was recalled to active duty and served as special advisor to the Secretary of the Treasury, 1939-40. Following the attack on Pearl Harbor, he was recalled again in January 1942 and served during World War II as special advisor on economic warfare to the Secretary of the Navy. For this service, he was awarded the Legion of Merit in 1945.[11] His citation described his service, as follows

"For exceptionally meritorious conduct in the performance of outstanding services to the Government of the United States in determining the policies and coordinating the joint activities of the Navy Department and Foreign Economic Administration (formerly the Board of Economic Warfare) in waging economic warfare against the Axis Powers from 12 Jan 1942 to the present time.

"Throughout this period, his thorough understanding of sea law and sea power, acquired during years of research in naval warfare (when he was adding the 'Life of Mahan' and other books to our naval literature) enabled him to indicate precisely how control of the sea could be used to maintain and increase the economic life of a nation; a zealous naval officer, he consistently pressed for the rigorous use of control of the sea by the United Nations to deny supplies and ammunition to the Axis Powers.

"He not only contributed materially to a correct understanding of the law of blockade but his persistent presentation of the facts concerning the aid received by Axis Powers from the European neutrals was a large factor in suppressing this un-neutral traffic. His action reduced the economic resources available to the Axis, their ability to continue the war and definitely assisted in shortening the duration of the war.