William McKinley was the 25th President of the United States, serving from March 4, 1897, until his assassination on September 14, 1901, after leading the nation to victory in the Spanish-American War and raising protective tariffs to promote American industry. Learn more about the 25th President of the United States. Learn more about William McKinley's spouse, Ida Saxton McKinley. This book also features some of his great quotes that you will find inspiring.