[4] In 1812, Ingersoll was elected as a Democratic-Republican to the Thirteenth Congress, where he served as chairman of the United States House Committee on the Judiciary.

He was an unsuccessful candidate in 1837 for election to fill the vacancy caused by the death of Francis J. Harper in the Twenty-fifth Congress.

He served as chairman of the United States House Committee on Foreign Affairs during the Twenty-eighth and Twenty-ninth Congresses).

[8] Beginning in 1845 Ingersoll wrote several editions of a history of the War of 1812, including descriptions of the Congressional investigation of the Burning of Washington in 1814.

He also published numerous anonymous contributions to the Democratic Press of Philadelphia, and to the National Intelligencer of Washington, on the controversies with England before the War of 1812 (1811–15).