How do wars start? Sometimes, it's because leaders apply the wrong lessons of history.
Then US President Lyndon Johnson, for example, scribbled to himself while deliberating whether to intervene massively in Vietnam: "To give in = another Munich. If not here - then Thailand." Mr Johnson's old friend, Senator Mike Mansfield, repeatedly warned him that Vietnam was not "another Munich", but his warnings fell on deaf ears. The net result was a war lost, and over 50,000 American soldiers and millions of Vietnamese killed.