Such a confrontation is occurring today at the very heart of the European "bloodlands", in Poland, where the trauma of the Nazi and Soviet genocides is relived in intense public debates.
The triggers to these debates are two new films about the fate of the Polish Jews, the controversial Second Harvest and In the Dark, as well as the wave of publications by Polish historians revealing forgotten -and often carefully hidden - wartime atrocities.
One episode of this dark past deserves attention. Seventy years ago, on 10 December, 1942, the Polish government in exile in London issued its "Note addressed to the Governments of the United Nations" and titled "The Mass Extermination of Jews in German Occupied Poland". It was the first public document of the Holocaust based on systematically collected and authenticated evidence, including the eyewitness accounts of Polish underground fighters Witold Pilecki and Jan Karski.
It was also a desperate plea for action to stop the German atrocities. The note painted a frightening picture of the Nazi death machine moving into top gear:
"Most recent reports present a horrifying picture of the position to which the Jews in Poland have been reduced. The new methods of mass slaughter applied during the last few months confirm the fact that the German authorities aim with systematic deliberation for the total extermination of the Jewish population of Poland and of the many thousands of Jews whom the German authorities have deported to Poland from Western and Central European countries and from the German Reich itself."
The brutality of the Nazi extermination program was best demonstrated in the Warsaw ghetto established by the German occupiers in October 1940.
Its helpless Jewish inhabitants - about half a million of them - were not only robbed of their possessions, humiliated and isolated, they were also starved and subjected to the daily terror of deportations and executions. With the outbreak of the German-Soviet war, mass murders spread further east.
Moreover, as the note warned, the Germans applied new methods of mass killing, such as poison gas and electrocution. The note ended with a desperate plea for help in stopping the atrocities and "condemning the crimes committed by the Germans and punishing the criminals" as well as for restraining Germany "from continuing to apply her methods of mass extermination".
Tragically, the plea fell on deaf ears. Poland was dismembered and terrorised by the joint German and Soviet invasion and brutal occupation. German troops controlled continental Europe and parts of North Africa. Stalingrad was under siege.
The mass exterminations perhaps may not have been stopped, but they could have been slowed. Pilecki urged a commando-style liberation of the death camps while Karski called for the bombing of railways. Though the effectiveness of such actions remains debatable, with depressingly few exceptions there was no serious attempt to arrest the Holocaust.
How could one explain this inaction? Incredulity? Indifference? Pragmatic military prioritising? Probably all of these combined. Early reports of systematic mass extermination of Jews, as well as Poles, Belorussians, Ukrainians and many others, were either dismissed or treated as "exaggerations".
British foreign secretary Anthony Eden told Karski that Britain had "already done enough by accepting 100,000 refugees"; US president Franklin Roosevelt established an advisory board; US Supreme Court judge Felix Frankenfurter, himself a Jew, responded famously: "Mr Karski, I am unable to believe you."
The truth is that no serious action was undertaken and the authors of the reports were largely ignored. Pilecki was subsequently arrested by the communist authorities in Poland, tortured and executed. Karski, frustrated by the lack of Allied response, went into exile in the US, though his heroism was later honoured in the US, Israel and post-communist Poland.
His sombre judgment provides perhaps the best summary: "The Jews were abandoned by all governments, church hierarchies and societies, but thousands of Jews survived because thousands of individuals in Poland, France, Belgium, Denmark (and) Holland helped to save Jews.
"Now every government and church says, 'We tried to help the Jews', because they are ashamed."
Have we learned from this episode? Memories of Rwanda's genocide, the Srebrenica massacre and the contemporary horrors in Syria do not inspire optimism. It is time to re-read Karski's warning.
Jan Pakulski is professor of sociology at the University of Tasmania and president of the Australian Institute of Polish Affairs
