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Germany observes no official holiday on November 9th, the day when, twenty years ago, crowds of stunned, delirious East Germans breached the Berlin Wall. This is because November 9th is also the date on which Kaiser Wilhelm abdicated, in 1918, two days before Germany’s defeat in the First World War. On November 9, 1923, Hitler attempted to overthrow the Weimar Republic, in the Munich Beer Hall Putsch. In 1938, November 9th was the Night of Broken Glass, when Nazi gangs attacked Jews and their property across Germany and Austria, foreshadowing the genocide to come. The German calendar is appropriately inconvenient: nothing good is conserved without the active remembrance of something bad. The British writer Timothy Garton Ash has called 1989 the best year in European...