This nation ceded some of its American territory by the Treaty of San Ildefonso, and the first treaty between it and the United States was named for the brother of a Federalist Presidential candidate, Thomas Pickney.
John Eaton served as US Ambassador to this country after being removed as Secretary of War, while literary figures to hold this ambassadorship include David Humphreys and Washington Irving. One treaty between the United States and this nation resulted in the Insular Cases, while another involved a dispute over the Sabine River. This nation ceded some of its American territory by the Treaty of San Ildefonso, and the first treaty between it and the United States was named for the brother of a Federalist Presidential candidate, Thomas Pickney. For ten points, name this European country the US defeated in an 1898 war.
John Eaton served as US Ambassador to this country after being removed as Secretary of War, while literary figures to hold this ambassadorship include David Humphreys and Washington Irving.
{Spain} [accept: {Espana}]