Tomorrow, the leaders of many Western nations will gather on the shores of Normandy to observe the 40th anniversary of the Allied invasion of Nazi-occupied Europe.
But the Soviet Union, meanwhile, is engaged in a major effort to belittle the contribution of Western countries during World War II.
The campaign, involving many organs of the government-controlled press here, holds that Western powers delayed the invasion in order to allow the Germans time to inflict more damage on the Soviet Union - and only belatedly mounted the Normandy invasion to grab part of the credit for defeating Hitler.
''The outcome of the war had already been decided'' before the June 6, 1944, invasion, according to a retired Soviet general interviewed by Tass, the official government news agency. Those who see history in a different way are, according to Soviet writers, ''falsifiers'' or representatives of ''bourgeois'' mass-information media who blend ''deliberate distortions of history together with ill-intentioned lies.''
The Soviet Union has long held that the Red Army bore the brunt of World War II (which is known here as the ''Great Patriotic War'') - and that it played the major role in defeating the forces of Adolf Hitler. But lately the campaign has become louder and shriller in an obvious effort to counter the planned observances of the 40th anniversary of D-Day, the first day of the Allied assault on the European mainland.
On June 6, President Reagan will join French President Francois Mitterrand, Queen Elizabeth, and Canadian Prime Minister Pierre Trudeau at ceremonies in Caen, France, to mark the occasion.
But an official journal of the Soviet Defense Ministry has already dismissed the ceremonies as a ''pompous propaganda campaign.'' And Izvestia, the official government newspaper, recently carried an article that drew crude parallels between Hitler and President Reagan, implying that the two men share the ''distorted consciousness of a maniac killer.''
For years, the Soviet Union has complained that its contributions in World War II have been consistently understated by contemporary historians. The claim is, according to some military analysts, not without some justification.
In fact, this country suffered grievous losses during the war: Some estimates run as high as 20 million people. The losses in a single Russian city - Leningrad - were calculated at nearly 1.5 million people. That, according to one account, was at the time equal to ''the entire war losses suffered by the United States in the whole of its history.''
Wartime losses of young Russian men are still felt in this country, notably in the form of a male-female population imbalance that will persist for several more generations. The country is studded with war memorials and statues, and memories of the conflict can even now provoke emotional responses, especially for Russians.
A kerchiefed Russian babushka, for example, interviewed on a Moscow street, broke down into tears when recalling, ''I lost two brothers during the war.'' Then, she added as she hurried away, ''and now look what Reagan is doing. . . .''
That is precisely the connection the Soviet leaders would like more people to make.
During the current press campaign, the Soviet government is suggesting that today, as in 1944, the US is no real friend of Europe. The current observances of D-Day, the Defense Ministry's ''military-historical journal'' argues, are aimed at trying to ''dispel the anxiety of Europeans who, according to Washington's strategic plans, are to be the first to be burned in a 'limited' nuclear war in Europe.''
Pravda, the official Communist Party newspaper, recently carried an article by a former war correspondent identified as Daniil Kraminov. In it, he wrote that ''moral preparations'' are under way ''for a new, this time, nuclear war, which dooms Europe and the European civilization to destruction.''
That, of course, dovetails with Moscow's ongoing propaganda efforts against the stationing of new American-supplied nuclear missiles to Europe.
Another theme of the current press campaign is the suggestion that Western leaders were culpable for their encouragement of Hitler's ambitions. Kraminov, in the Pravda article, argues not only that US banks financed Hitler's wartime mobilization, but also that the US blocked early efforts by the Soviet Union to provide for a ''collective defense'' of Europe from Hitler's advance. (Notably, there is no mention in any of the articles about the Aug. 23, 1939, Soviet-German nonagression pact, which many historians view as having paved the way for the subsequent Nazi invasion of Poland.)
Kraminov further argues that ''without that aid and open encouragement from reactionary circles of the USA, Great Britain, and France . . . Hitler would not have dared and could not have possibly undertaken the military adventures which brought untold suffering, sacrifices, and destruction to Europe.''
The current press campaign also makes much of alleged ''foot- dragging'' by the Allies in opening the ''second front'' against Germany in 1944. The military-historical journal claims that ''published documents make it clear'' that the Soviet Union pushed the Allies to open up a front in Europe as early as July 1941 and that the Allies agreed to do so in 1942.
Why the delay until 1944?
In an interview with Tass, Col.-Gen. Ivan Kuzovkov, identified as a wartime commander, argues that subsequent events have made it clear that the West ''deliberately made the Soviet people shoulder the hardships of war and hoped to see the Soviet Union bled white.''
In fact, he continues, the advance of Soviet troops actually forced the Germans to divert troops away from Normandy and thus paved the way for the successful Allied landing there. But, he said, as a practical matter the Normandy invasion ''was an important but auxiliary factor'' in the war effort because the Soviet Army had already doomed Hitler to defeat.
''Why was the second front opened in 1944 and not later?'' the military-historical journal asks. Because, according to the journal, the prospect of a Soviet victory without Allied help ''frightened the monopolistic circles of the US and Britain and made them hurry up with the opening of the second front in Normandy.''
Indeed, pro-Soviet, Australian-born author James Aldridge writes in Izvestia, ''The opening of the second front was partially caused by fear. In Western political circles they understood that the Red Army in its victorious offensive was far from being exhausted and could rout the enemy on its own.''
In a similar vein, Tass rebukes Ronald Heiferman, author of ''World War II,'' for ''falsifying historical events.'' Heiferman, according to Tass, suggests that the Russians pressed the allies to open a second front in Europe to prevent the collapse of the Red Army ''under a Nazi onslaught.''
This is simply another example of how ''falsifiers are rewriting history for the sake of political objectives,'' says Tass.