Adams–Onís Treaty
Irwin was elected as a Republican to the Thirteenth and Fourteenth Congresses. In 1817, Irwin assisted in the establishment of a short-lived revolutionary government on Amelia Island. He died in Fernandina, Florida in 1818, which was then a part of the Spanish-controlled territory of Florida (Spain ceded Florida to the U.S. in 1821 as a result of the Adams–Onís Treaty).