As a politician he led a realignment that made his Republican Party largely dominant in the industrial states and nationwide until the 1930s. He presided over victory in the Spanish–American War of 1898; gained control of Hawaii, Puerto Rico, the Philippines and Cuba; restored prosperity after a deep depression; rejected the inflationary monetary policy of free silver, keeping the nation on the gold standard; and raised protective tariffs to boost American industry and keep wages high.
A Republican, McKinley was the last president to have served in the American Civil War; he was the only one to begin his service as an enlisted man, and end as a brevet major. After the war, he settled in Canton, Ohio, where he practiced law and married Ida Saxton. In 1876, McKinley was elected to Congress, where he became the Republican expert on the protective tariff, which he promised would bring prosperity. His 1890 McKinley Tariff was highly controversial and, together with a Democratic redistricting aimed at gerrymandering him out of office, led to his defeat in the Democratic landslide of 1890. He was elected governor of Ohio in 1891 and 1893, steering a moderate course between capital and labor interests. 