[1] A career foreign service officer, he began serving as a diplomat in 1903,[2] and arrived in Copenhagen on 18 July 1917, to take up the position of Counselor at the US Legation there.

Less than five months later, upon Minister Maurice Egan's departure on 16 December, he became Chargé d'Affaires and the ranking US representative in Denmark.

He remained Chargé for over a year, until the arrival of the new US Minister, Norman Hapgood, on April 16, 1919.

On September 18, 1919, Grant-Smith left Copenhagen, and was declared eligible for a new diplomatic assignment.

Grant-Smith was appointed to the post in September 1922 by President Warren G. Harding, and arrived in Tirana in December of the same year.