Professor Geoffrey Roberts explains why the Soviet-German conflict on the Eastern front was the decisive theatre of the Second World War: without it, Nazi Germany would certainly have taken much longer to defeat. Despite this, outside military accounts, the Red Army's struggle has been overshadowed in Western narratives by the Anglo-American war effort. Professor Roberts corrects the balance.

The music in this episode is from Ida Pinkert's 'Four Songs', played by the Nimrod Ensemble of Berlin as part of the Lebensmelodien project, which seeks to rediscover the lost music of composers affected by the Holocaust (www.lebensmelodien.com).