The Londonderry City by-election of 1872 was held on 23 November following the resignation of incumbent Liberal Party member of parliament Richard Dowse to become a Baron of the Exchequer. The Liberal vote was split as their candidate, Christopher Palles, was considered by Catholics as a "priest-hunter" for his prosecution of clergy as Attorney-General and denounced by Protestants for his views on education along denominational lines. The election was won by the Irish Conservative Party's Charles Lewis who secured a 174-vote majority. The election was the first Irish election to the British Parliament to be held by secret ballot.