Yes, enmities going back to medieval times can be healed.

Any skeptic who doubts this should visit Gdansk, where Hitler's Wehrmacht attacked Poland and started World War II on Sept. 1 70 years ago. Today, as a result of brave individual initiatives – and later of government policy – Poles and Germans are friends and allies.

And yes, there is also strong resistance to dropping old enmities.

Any doubter of their persistence should also visit Gdansk. For weeks there has been a drumbeat in Russian media blaming Warsaw for alleged collusion with Berlin against Moscow prior to that 4:45 a.m. German attack in 1939.

Russian Prime Minister Vladimir Putin abruptly softened the tone in the Polish daily Gazeta Wyborcza on the Sept. 1 anniversary, calling "immoral" the cynical Hitler-Stalin pact of August 24, 1939, that carved up Poland and the Baltics as a prelude to the German invasion of western Poland a week later and the Soviet invasion of eastern Poland three weeks later. Putin's new smile met with considerable Polish skepticism.

World War II killed 6 million Poles, half of them Jews. That statistic can be reconfigured: the war killed some six million Jews, half of them Poles. Of all the countries that mourned their losses among the more than 50 million civilian and military dead, Poland suffered the highest ratio of war deaths per population.

This tragedy was the culmination of Poland's unfortunate location between powerful Russians and powerful Germans. In the 18th and 19th centuries, Russia and Prussia (and Austria) conspired for 123 years to extinguish the country of Poland altogether. After World War I, it was resurrected, only to succumb to the conspiracy of Hitler and Stalin in 1939.

For decades after World War II, Poles were hostile to Russians – discreetly, as befitted a Communist client of Moscow – and to Germans, ostentatiously. Millions of German civilians who endured the revenge of expulsion in 1945 from ancestral homesteads in postwar western Poland and elsewhere in Central Europe – 14 million, of which 2 million did not survive their trek west – reciprocated the hostility.

The mutual Polish-German revulsion seemed implacable. But in the 1950s, the old enemies of France and Germany began to rethink their habit of periodic wars. Both Germans and Poles noted this successful experiment, and in 1965 the Catholic bishops of both countries issued a controversial call for Polish-German reconciliation. "We forgive, and we ask to be forgiven," the most famous sentence read.

The next step of rapprochement came a generation later. When the Solidarity trade union mounted its famous strike at the Gdansk shipyard in 1980, wrestled the ruling Polish Communists to an unprecedented political compromise, and then was outlawed in 1981, ordinary West Germans responded in a wave of sympathy. They donated clothes and food to volunteer truckers for distribution to needy Poles. They sent hundreds of thousands of aid packages to Warsaw and Krakow and Gdansk at reduced German government postal rates.

With this evolution, ordinary Poles began to distinguish for the first time between Germans in the (Communist) East and in (democratic) West Germany. The West Germans lost their image as ogres. The East Germans, whose government had lobbied the Soviet Union to punish the restive Poles, did not.

By the time the Berlin Wall fell in 1989 it was almost as inconceivable that Poles and Germans might again fight each other as it was that French and Germans might do so. It was possible to speak German on the streets of Polish cities without evoking dark looks from bystanders. And in a fashion that would have been scandalous even five years earlier, it was common to see Polish teenagers follow the European fad of wearing contemporary German Army jackets.

Moreover, numerous Germans for the first time visited their confiscated family homes in Silesia (a historic region of Central Europe, now mainly in southwestern Poland), not to reclaim them, but to make the acquaintance of their current Polish owners – and in thousands of cases to form lasting friendships. Even the fulminations of the anti-Polish right in Germany and the anti-German right in Poland failed to ignite wider national resentments.

In 2004, as Poland entered the European Union that had reconciled Germany and France so spectacularly, Warsaw's strongest sponsor was Berlin.

At this year's commemoration of the German attack on Gdansk, Chancellor Angela Merkel was warmly welcomed by officials and ordinary Poles alike. Mr. Putin was politely welcomed, by officials alone.

Putin, it seems, still has to figure out why the Germans and Poles are no longer enemies.

Elizabeth Pond, a Berlin-based journalist, is the author of "The Rebirth of Europe."