Bret Stephens: This is how World War III begins

The usual date given for the start of World War II is Sept. 1, 1939, when Hitler invaded Poland after the signing of the Molotov-Ribbentrop Pact. But that was just one in a series of events that at the time could have seemed disconnected. Among them: Japan’s invasion of Manchuria in 1931. Italy’s invasion of Abyssinia in 1935. The remilitarization of the Rhineland in 1936 and the Spanish Civil War, which started the same year. Anschluss with Austria and the Sudeten crisis of 1938.