From 1899 until the American entry into World War II, U.S. presidents sought to preserve China's territorial integrity in order to guarantee American businesses access to Chinese markets -- a policy famously known as the "open door." Before the Russo-Japanese War in 1904, Americans saw Japan as the open door's champion; but by the end of 1905, Tokyo had replaced St. Petersburg as its greatest threat. For the next thirty-six years, successive U.S...