President Andrew Johnson appointed Ewing as U.S. Minister to Holland, where he served from 1866 to 1870. This appointment may have drawn the ire of the Radical Republicans, for Speaker of the House James G. Blaine urged President Ulysses S. Grant that Ewing be recalled and replaced with his brother, Charles Ewing. Blaine told the President that Hugh was 'acting badly'. Blaine himself was disingenuous, having represented to prominent politicians in Ohio including Senator John Sherman that he was doing everything possible to nominate his close personal friend, former Ohio General Roeliff Brinkerhoff, for the post. Nonetheless, Blaine's request to recall General Ewing was never acted upon, possibly due to the influence of his sister, whose husband General Sherman was a very close friend to President Grant. Ewing was related to Blaine through Blaine's mother Maria Louise Gillespie Blaine.