Under the veneer of western unity in support of Ukraine, reactions to the war across Europe have been informed by different countries’ readings of their own history, of earlier conflicts on this continent, and by their conceptions of Russia’s national character. There is no automatic consensus within democratic societies about the lessons of the past, nor should there be. Remembrance is often selective, and the way ahead involves a discussion about what went wrong before. Nowhere has this process of revisiting the past in search of the right decisions for the future been more fraught since the Russian invasion than...