At the advent of the Revolution, Carmichael lived in London. Met Arthur Lee, who entrusted him with dispatches for America.
Poor health caused him to remain in Paris instead of returning to America. In France, he served as secretary to the American Commissioners (Lee, Silas Deane, and Franklin).
Returned to America in 1778 and served in the Continental Congress before becoming secretary to John Jay. Accompanied Jay to Spain in 1780. Until 1794, served as diplomat in Spain, where he died.
Born in Queen Anne County, Maryland. Married to — Stirling. Married to Antonia Reynon; one daughter.