History doesn’t repeat itself, but it rhymes, quipped Mark Twain. As with most of Twain’s homilies, it’s funny because it’s true. So as the world commemorates the Guns of August—that is, the start of World War I-- history is not repeating itself. But the world today does seem to have a certain poetic, unrhymed iambic pentameter in common with the Great War. “With a dimming of the lights and ceremonies across this country and in Belgium, monarchs, princes, presidents and citizens prepared on Monday to mark the day 100 years ago when Britain entered World War I at the start...