In the opening salvo of an autumn campaign to halt the deployment of new nuclear missiles in West Germany, up to 1,000 peace protesters today began a three-day blockade of an American airfield that is expected to serve as a base for Pershing II missiles later this year.

The demonstrators, including novelist Heinrich Boell, a winner of the Nobel Prize, marched to the two main entrances just before dawn and sat down to halt military traffic. The action was timed to coincide with the anniversary of the moment 44 years ago when Hitler's tanks smashed into Poland.

"It's a symbolic way of reminding the world that another war may be imminent," said Erhard Eppler, a leading Social Democrat active in the antimissile crusade.

Throughout the day, the protesters strummed guitars, created peace signs and waved amiably to U.S. soldiers across a thicket of barbed wire.

But no military vehicles tried to pass the blockade and only a skeleton staff of American soldiers appeared to be protecting the base. This caused speculation that missiles and sensitive equipment had been moved out before the demonstration.

West German police officials said they would dislodge the protesters only upon request by U.S. authorities, who seemed to be making every effort to avoid a confrontation.

"If anything newsworthy happens, it's not going to be on account of us," Maj. Tony Maravola, a public affairs officer for the 56th Field Artillery Brigade, which uses the base, told reporters.

As they traded shifts sitting in front of the entrances, a number of the protesters, seemingly vexed by the passivity of soldiers and police, began to show signs of boredom and frustration.

But Petra Kelly, a member of parliament representing the Greens Party and a driving force behind the antimissile campaign, insisted that any protest actions must not go beyond peaceful civil disobedience.

"It may be frustrating, but we believe only in peaceful protest against weapons of mass destruction," she said as she squatted before a sign that read "Father State makes Mother Earth kaput."

She and other leaders of the peace movement here admitted that they were dubious about their chances of preventing deployment of new missiles if arms control talks fail in Geneva.

"It's going to be a very long struggle," said Daniel Ellsberg, the American peace activist known for putting the "Pentagon Papers" into the hands of the press. "The odds are against us but they are still not zero."

Ellsberg said he believes there is "a real risk" that members of the peace movement in West Germany will grow disillusioned if pacifist methods fail to block deployment of the new missiles.

He shares the fear of some Greens Party leaders that if that happens, a small minority bent on violent tactics will seek to assert greater control of the antinuclear movement in West Germany.

The protest leaders said they think as many as 10,000 people may show up at the air base by Saturday. But for now, there was a palpable sense of disappointment in the fact that the protest seemed to have little impact on the authorities.

Some listless demonstrators passed the time forming peace insignias in the road with stones, while others placed flowers atop the barbed wire or simply sunbathed in meadows and cornfields.

Increasingly, the West German peace movement seems to be looking past the deployment of the new missiles and developing a strategy for getting rid of the rockets once they are installed.

"There will be unrest in this country as long as the missiles are here," said Eppler, who is seeking to forge a loose coalition of Greens and Social Democrats. "We may have to remain patient until some new American administration finds out that the political price of these weapons is not worth the military advantage they supposedly provide."

In Bonn, three peace activists from France, the United States and West Germany continued their month-long fast in front of the U.S. Embassy to protest the planned missile deployment.

On Wednesday, West German Chancellor Helmut Kohl sent a message urging them to abandon their fast.

"It shows that they are getting to Kohl's conscience," said Ellsberg. "If he lets them die, the fasters will bother him more than ever."

West German officials have predicted that the coming months could be a "hot autumn" of violent protests against the missiles, but some commentators suspect that these expressed fears were deiberately exaggerated so that a series of meek demonstrations might be interpreted as a victory for the authorities.

The antimissile movement plans to end its season of protests with a series of rallies and blockades that it says will attract 3 million people from Oct. 15 to 22.