SURPRIZE!!! The answer is 1871 and involved three lives lost over a diplomatic dispute that was not resolved until 1878
The Korean "Police Action" War started on June 25, 1950, and has never formally ended. A Cease Fire was enacted on July 27, 1953, but there was no formal surrender of the Communists to the UN Forces. Technically, there is still a war in Korea. Hal, US Army, South Korea, 1961-62.