[5] On January 27, 1919, Miles led the delegation of the Coolidge Mission which, on the way to Carinthia, visited the city of Marburg (today Maribor in Slovenia).

[7] Slovenian military units commanded by Rudolf Maister killed between 11[citation needed] and 13[8] German civilian protesters in a central Maribor square, during event known as Marburg's Bloody Sunday.

Regarding Carinthia, the Coolidge Mission focused on where to draw the future border between the newly formed Kingdom of Serbs, Croats and Slovenes and Austria.

The U.S. position before the Paris conference favored, like the British and French, a separation along ethnographic lines, i.e., a border along the river Drava (German: Drau), which would have split the economic and geographic region of the Klagenfurt basin.

In his field travels, he learned that many of the Slovene speakers in the region actually preferred to belong to Austria and had closer economic ties to the Klagenfurt area than to Slovenia.

From 1922 to 1925 he was military attaché at Constantinople in Turkey,[5] and was sent in 1924 to Teheran to investigate the murder of U.S. Vice Consul Robert Whitney Imbrie there.

[12] Miles was promoted to lieutenant colonel in the Regular Army in 1929 and to colonel in 1935[13] The March 1934 photo to the right, presents General Sherman Miles accompanying the Japanese statesmen Prince Iyesato Tokugawa, as Iyesato and his granddaughter as they honor America's Tomb of the Unknown Soldier Memorial in Arlington National Cemetery, Washington, D.C.[clarification needed] Prince Tokugawa (1863–1940) devoted his life to maintaining goodwill between Japan and the U.S. and other nations, and was so politically influential in Japan and internationally, that it was only after his death that Japan joined the Axis Powers in WWII.

Miles' suggestions to set up an espionage service were ignored until June 1941,[17][18] when U.S. President Franklin D. Roosevelt appointed William J. Donovan as Coordinator of Information.

The decoded "Magic" messages were top-secret and circulated only in a very select circle of ten people comprising the General Staffs of the Army and the Navy, the Secretary of War, and the President.

[17] The warnings that the General Staff sent to Hawaii failed to stress the urgency because MID themselves did not consider the contents of the "Magic" intercepts received prior to the attack as particularly significant at that time.

[29] In 1948, he wrote the article "Pearl Harbor in Retrospect" in the July 1948 issue of The Atlantic, in which he gave his perspective on the events just prior to the attack.

[2] He died at the hospital in Beverly, Massachusetts after long illness[1] and was buried at Arlington National Cemetery[31] in the Miles Mausoleum on October 12, 1966.