WARSAW, Poland — Back home in Germany, Erika Steinbach is hardly a household name. But in neighboring Poland she is a national hate figure, caricatured on magazine covers as a Nazi in SS uniform.

Her offense, in Polish eyes, is that she claims to speak for the millions of ethnic Germans who were expelled from their homes in Poland and elsewhere in Eastern Europe after World War II. These accusers say she is revising history and drawing a moral parallel between the cruelties the Germans inflicted and the sufferings they later endured.

The recriminations go to the heart of the resentments that still bubble up from the war that broke out with Hitler's attack on Poland on Sept. 1, 1939.

Today, as Polish, German and Russian leaders join on Tuesday to mark the anniversary, Polish-German relations are at one level an idyll of open borders and shared membership in the prosperous, democratic European Union.

But at another level, they are one rancorous episode after another: a Polish prime minister demanding greater voting power in European forums to make up for Poland's war-related loss of population; a German magazine article that stirs Polish outrage by saying Germany had the willing help of Poles and others in executing its genocidal actions; and now a new museum in Berlin, championed by Steinbach, that will exhibit the hardships of the world's refugees through history, especially the wartime Germans.

Steinbach, 67, strenuously denies minimizing Poland's afflictions. But she is a lightning rod for Poles' fears that future generations of Germans will grow up in a historical muddle about the war and its aftermath.

"We'll probably reach a point — and we are hearing this already — that Germans suffered equally because someone expelled them from somewhere and that they were killed as well," complains Jacek Patoka, a 42-year-old Polish businessman.

What irks the Poles most is Steinbach and her Federation of the Expellees, the group that demands recognition of the suffering inflicted on some 14 million Germans when the postwar borders were redrawn and they were driven out of their homes.

When Steinbach pushed for the Berlin museum, Poland's government was indignant, seeing it as a sign that Germans were trying to play down their crimes and highlight their own suffering and resistance to Hitler's regime.

"We don't like these activities," said Romualda Tudrej, 82, who fought in Poland's anti-Nazi resistance. "The Germans are . . . changing history."

The war left Poland feeling massively betrayed — by its Western allies who failed to come to their aid; by the Soviet army that first invaded it, then stood aside as the Germans crushed the country; and by the postwar settlement that opened the way to 40 years of communist dictatorship.

Poland today has 38 million people to Germany's 82 million, which qualifies it as medium-sized in a European Union where voting is weighted by population size. And even that ties in to the war. In arguing in 2007 for enhanced voting rights, the then-prime minister, Jaroslaw Kaczynski, argued: "If it hadn't had to live through the years 1939-1945, Poland would today be a country of 66 million."