Do we need another wrist-breaking book about Adolf Hitler, the Third Reich and the second world war? Since Ian Kershaw published his two-volume biography of the Führer 20 years ago, there have been at least a dozen similarly weighty tomes on the war by historians including Max Hastings, Andrew Roberts, Antony Beevor and Kershaw himself; not to mention more recent massive lives of the Nazi dictator by Brendan Simms and the German historians Peter Longerich and Volker Ullrich.