ethnic cleansing of Poles in his Gau – showed both how Hitler set events in motion, and how his Gauleiters could carry out totally different policies in pursuit of what they believed to be Hitler's wishes. In Kershaw's opinion, Hitler's vision of a racially cleansed Volksgemeinschaft provided the impetus for German officials to carry out increasingly extreme measures to win his approval, which ended with the Holocaust. The Israeli historian Otto Dov Kulka has praised the concept of "working towards the Führer" as the best way of understanding how the Holocaust occurred, combining the best features and avoiding the weaknesses of both the "functionalist" and "intentionalist" methods. Thus, for Kershaw, Hitler held absolute power in Nazi Germany due to the "erosion of collective government in Germany", but his power over domestic politics became more challenging to exercise due to his preoccupation with military affairs, and the rival fiefdoms of the Nazi state fought each other and attempted to carry out Hitler's vaguely worded wishes and dimly defined orders by "Working Towards the Führer". Later career Kershaw retired from full-time teaching in 2008. In the 2010s, he wrote two books on the wider history of Europe for The Penguin History of Europe series: To Hell and Back: Europe, 1914–1949 and The Global Age: Europe, 1950–2017. Honours and memberships Fellow of the British Academy Order of Merit of the Federal Republic of Germany, 1994 Winner of the Wolfson History Prize, 2000, for Hitler, 1936–1945: Nemesis (Allen Lane) Co-winner of the British Academy Book Prize, 2001 Fellow of the Royal Historical Society Member of the Historical Association Fellow of the Wissenschaftskolleg zu Berlin 2002, appointed Knight Bachelor in the 2002 Birthday Honours for services to History 2004, a collection of scholarly essays in Honour of Sir Ian Kershaw was published. 2005, Elizabeth Longford Prize for Historical Biography for Making Friends with Hitler: Lord Londonderry, the Nazis and the Road to War 2012, Leipzig Book Award for European Understanding (together with Timothy D. Snyder) 2018, Charlemagne Medal Works Bolton Priory Rentals and Ministers; Accounts, 1473–1539 (ed.) (Leeds, 1969) Bolton Priory. The Economy of a Northern Monastery (Oxford, 1973) 'The Great Famine and agrarian crisis in England 1315-22' in Past & Present, 59 (1973) "The Persecution of the Jews and German Popular Opinion in the Third Reich" pp. 261–289 from Yearbook of the Leo Baeck Institute, Volume 26, 1981 Popular Opinion and Political Dissent in