SOPRONPUSZTA, Hungary (AP) It was a picnic that changed the course of history.

Twenty years ago, members of Hungary’s budding opposition organized a picnic at the border with Austria to press for greater political freedom and promote friendship with their Western neighbors.

Some 600 East Germans got word of the event and turned up among the estimated 10,000 participants. They had a plan: To take advantage of an excursion across the border to escape to Austria.

Hungarian President Laszelo Solyom and German Chancellor Angela Merkel took part in festivities Wednesday marking the 20th anniversary of the “Pan-European Picnic,’’ which helped precipitate the fall nearly three months later of the Berlin Wall.

“Hungarians gave wings to the East Germans’ desire for freedom,’’ Merkel told an audience that included politicians, diplomats, former East German refugees and several of the picnic’s organizers.

One of the key factors allowing the Germans to escape: The decision by a Hungarian border guard commander not to stop them as they pushed through to freedom.

“It was an incredible experience for them,’’ said the guard, Lt. Col. Arpad Bella, remembering the scene as the East Germans marched up the road to the border gates at Sopronpuszta and crossed into Austria.

“They embraced, they kissed, they cried and laughed in their joy. Some sat down right across the border, others had to be stopped by the Austrian guards because they kept running and didn’t believe they were in Austria,’’ said Bella, 63, during an interview where the gates once stood.

Bella said he and five of his men had been expecting a Hungarian delegation to cross by bus, visit a nearby Austrian town as a symbol of the new era of glasnost — or openness — under reformist Soviet leader Mikail Gorbachev, and return to Hungary.