European neighbors Poland and Russia have both a shared, and a strained, history together. Both nations are Slavic, they speak similar languages, and have lived in relatively the same way throughout history. Over various periods of history, both Poland and Russia have conquered each other's territory. Despite all the similarities, however, there are sharp contrasts. Poles are Roman Catholics, and therefore use the Latin alphabet in their script, as well as being a very Western-oriented country; Russians are of the Orthodox religion, which has a centuries-long hatred of Roman Catholicism, and therefore write using the Cyrillic alphabet. In addition, Russia is oriented towards the East, towards Byzantine for its religious history, and the hordes of Mongolia for its political history. The centuries of conquering each other, as well as totally oppsite ways of thinking, have left a long mark of distrust between the peoples of these two countries.
In more recent history, relations between Russia and Poland have been even more complex. Poland has found itself caught between two powerful countries, and the center of a tug-and-war game between the capitalist and socialist superpowers of the world. Throughout most of the 20th century, Poland projected a political image of an ally of Russians and the whole Soviet Union, but behind the scenes, quite a different situation existed. After a combination of World War I and the October Socialist Revolution in Russia, it seemed as if Poland would be left alone by both of its powerful neighbors. Germany was destroyed during the war, and Russia was in the middle of devastating civil wars during the construction of the Soviet Union. During the 1920s and 1930s, however, Poland found itself stuck between two of the most powerful leaders of the entire century - Germany's Adolf Hitler and the Soviet Union's Josef Stalin.
World War II saw Poland invaded from all sides, and eventually moved to a different place on the map when its borders were shifted to the west, taking territory away from Germany and providing more land for the Soviet Union. The country was first invaded from the west by Hitler's Nazi soldiers. While laying waste to Poland, Hitler had his eyes on the USSR. Despite a tentative non-aggression pact signed between Germany and the Soviet Union to give Stalin some feeling of protection, Hitler had no intention of keeping his word. In 1941, Hitler began his massive invasion of the Soviet Union. So massive was Germany's attack against the USSR that the war is not just known as World War II in the Soviet Union - it is named the Great Patriotic War, in reference to the massive suffering of the country, followed by a miraculous buildup of defensive and offensive military power, culminating in Soviet liberation of Europe all the way to Berlin itself.
This is where the most serious and current problems in Polish-Russian relations begin. As a result of the Soviet liberation of Germany, Poland had been overrun by soldiers of both the Nazi army and the Soviet Red Army. Germany was again defeated, the Soviet Union was a victorious superpower, and Poland was caught in the middle. The passionately anti-Communist American president Truman tried to prevent any Soviet influence in Poland, knowing he needed the support of Polish Americans to keep him in office, as well as refusing to allow the socialist Soviet Union to have any upper hand over the United States, but ultimately, failed. After breaking a series of promises to Stalin during the war, which resulted in heavy Soviet losses, Truman was now powerless to prevent Stalin from exacting his reparations. After being invaded for centuries by Western European powers, Stalin decided that the borders of Russia, Belarus, Ukraine, and the whole Soviet nation, needed to be protected. For the first time in all of history, this was accomplished by the creation of a political buffer zone across all of central Europe.
Since the October Socialist Revolution that brought down the autocratic Russian Empire, communist parties came to existence throughout Europe. However, before World War II, only the USSR could claim communism as its ruling mandate. After the war, Stalin needed to create a buffer zone around the European borders of the Soviet Union to provide a guaranteed defense against any further invasions into Soviet territory from the west. For the entire country, this idea received widely popular support. The Great Patriotic War was especially devastating for the Soviet Union, and no one wanted to see a repeat of the death and destruction caused by World War II. Having started the war not only totally unprepared militarily, the USSR was also seriously behind the West in technological and economic advancement. By 1945, however, the Soviet flag was flying over the Reichstag, Soviet military power was admired and feared the world over, and the Soviet leadership was finally in a position to ensure that such a violent attack against the USSR would never happen again.
To create this buffer zone, Stalin needed the unquestioning political support of his western neighbors. This especially included Poland, which has always been the gateway to invasions of Russia from the west. To get this needed political support, the Soviet Union assisted the existing communist parties to come to power throughout all of central Europe. Within a few years, socialism and alliances with the Soviet Union had been established in the Soviet zone of Germany, Czechoslovakia, Hungary, Bulgaria, Albania, Yugoslavia, Romania, and, of course, Poland. This was a major change for these countries, most of which had been Western-oriented for quite a long time. To have their political, economic, and social influences now coming from the East, especially from "backwards" Russia, was quite a shock for the citizens of these new socialist territories.
For Poles especially, this was not a change that was going to be accepted willingly. Even though Poles and Russians are both Slavs, and practically neighbors, I already mentioned that Poland is Roman Catholic, and therefore Western-oriented, and Russia is Orthodox and Eastern-oriented. On top of the territorial disputes of the past, this created an environment hostile towards Russia, and especially the Soviet Union, in Poland. For the Soviet Union, though, it was a guarantee of a stable western border, and most importantly - protection from the conquering armies of Western Europe.
Poles felt this "conquering" of their country by Russians, as well as the implimentation of socialism, which ran contrary to the established Western way of doing things, to be the ultimate indignity. Thus, Poles felt that they had lost even their homeland. Soviets, as well as most Russians today, however, have a very different view on things, all resulting from experiences from the Great Patriotic War. Not just villages, but even major cities, such as Kiev and Minsk, were entirely wasted during the war and had to be totally rebuilt from scratch. Leningrad endured unimaginable suffering during the 900-day blockade imposed by Hitler, and Moscow itself was in danger of being overrun by Nazi forces. Further south, the region of the Volga River also sustained tremendous damage and death. It is here, though, especially in the cities of Stalingrad and Kursk, where the Soviet Army was finally able to begin defeating the "invincible" army of Hitler's Third Reich.
It is this suffering, as well as the fact that the USSR was ultimately victorious in the war, that leads Russians to think that the creation of a buffer zone was the right thing to do. Poles, however, will never be able to forgive the Russians for what those in Poland consider to be half a century of occupation and domination by their neighbors to the east, over a border that has been uneasy for centuries.
Interesting and a full of humour: The Xenophobe's Guide to the Russians