Which war was William McKinley president during?

William McKinley served as President of the United States from 1897 until his assassination in 1901. During his presidency, the significant conflict that took place was the Spanish-American War, which occurred in 1898. This war marked a turning point for the United States, as it fought against Spain and ultimately gained control over territories such as Puerto Rico, Guam, and the Philippines. The conflict was fueled by American imperialistic ambitions and issues surrounding the treatment of Cubans under Spanish rule, which garnered significant public support for intervention.

The other wars listed occurred at different times in U.S. history: World War I happened from 1914 to 1918 long after McKinley's presidency; World War II took place from 1939 to 1945; and the Vietnam War spanned roughly from the late 1950s to the 1970s. Therefore, the Spanish-American War is directly linked to McKinley's time in office and exemplifies his administration's foreign policy direction.