If it’s thought of at all, the Korean War is seen in the United States chiefly as a "proxy in the cold war conflict." In fact it was at once a war of postcolonial succession, a war of national liberation, and a struggle involving regional and global powers, Millett declares. Not least, it was a war that cost more than three million lives, a toll exceeded in the 20th century only by the two world wars.

According to Korean folklore, the country has been invaded at least 600 times in the past three millenniums. Its location between Japan and mainland Asia made it a swinging door for passing armies of Chinese, Japanese, Mongols, Manchurians, and, later, Europeans and Americans. Nevertheless, the Kingdom of Choson ("land of the morning calm") survived from 1392 until 1910, when Korea became a Japanese colony.

The Korean War had its immediate roots in the 1920s, says the author, a military historian at Ohio State University, when rivalry sprang up between two national liberation movements. The "Christian-capitalist modernizers" owed much to the Christian missionaries who had been welcomed in the late 19th century as a counterweight to Japanese influence. After popular protests brought a million Koreans into the streets in 1919, Japan brutally suppressed the movement. That created an opening for the Marxist-Leninists. Conflict between the two groups broke into the open between 1927 and 1931, when the communists "subverted and betrayed" a popular nationalist association captained by their rivals.

The Korean War really began in 1945, Millett believes, as the two national liberation movements angled for influence in the Soviet and American occupation zones. Two leaders emerged: Kim Il-sung in the north and Syngman Rhee in the south. Kim Il-sung persuaded his Chinese and Soviet sponsors to support an invasion to "liberate" the south, which he launched in June 1950. But South Koreans, viewing the assault as yet another Chinese invasion, rallied to Rhee.

"The Korean War everyone knows" was thus a global, regional, and ideological struggle, but also very much a Korean affair. The world has seen similar "mixed" wars—in Algeria, Yugoslavia, Afghanistan—and it will see them again. But it must still learn to see them clearly.