The collection is being auctioned by Dickins Auctioneers in Buckinghamshire and is expected to fetch up to £20,000. Von Richthofen commanded the Condor Legion, the flag of which is seen here. It infamously bombed Guernica during the Spanish civil war, killing hundreds. In 1941, von Richthofen commanded a Luftwaffe division during Operation Barbarossa – the ultimately unsuccessful invasion of the Soviet Union.