He served as aide-de-camp, with the rank of colonel, to General William Henry Harrison, later president of the United States.

Green Clay Smith followed his father and maternal uncles into law and politics, serving at both the state and federal levels.

[4] John Speed Smith was elected to the state house of representatives in 1819, serving one term.

[1] Smith was elected as a Republican to the Seventeenth Congress to fill the vacancy caused by the resignation of George Robertson and served from August 6, 1821, to March 3, 1823.

[2][5] He was appointed as United States district attorney for Kentucky by President Andrew Jackson, serving 1828–1832.