Peace talks between the Taliban and the U.S. have brought back memories of the negotiations that led to the end of America’s war in Vietnam. They’re also reminiscent of an earlier effort by the U.S. to bring about a peace deal in Asia—specifically, in China after World War II. That effort ended in complete failure.

The U.S. goal in China was to save a pro-American ally, the Nationalist government of Chiang Kai-shek, from being overthrown by Mao Zedong’s communists. The Truman administration didn’t want to go to war to save...