WASHINGTON, Feb. 17, 2006—Marcel Duchamp's version of the Mona Lisa added a mustache and goatee to the Da Vinci original. Man Ray exhibited a flatiron with a row of tacks glued to the bottom.

Their work was typical of the art-as-rebellion movement they called Dada. A challenge to both artistic and political establishments of the early 20th century, Dada flourished in New York as well as western Europe.

More than 450 Dada works are getting their first big American exhibition Sunday, Feb. 19, at the National Gallery of Art.

Dada can mean various things in various languages: ''yes, yes'' in Russian and Romanian, a hobby horse in French, baby talk for ''daddy' in English. The name seems to have been chosen to mean nothing in particular.

The movement's first publicist, Romanian-French poet Tristan Tzara, gave a formula for writing a Dadaist poem: Choose a newspaper story of the right length, cut it up word by word, shake the words in a bag, take them out one by one and arrange them in the order they emerge.

Dada was born in the slaughter of World War I, and it had a basic motivation: fierce and bitter contempt for the old men who sent young men to kill one another for principles that had little or no meaning to artists. Dadaists said traditional art bore much of the blame for the war, and they did their best to subvert it.

Duchamp, the most prominent of the Dadaists in New York, made both political and artistic points.

On Jan. 23, 1917, President Wilson was still trying to persuade both sides to move to a ''peace without victory.'' But the German High Command was preparing an announcement of intensified submarine war. That made it almost inevitable that the United States would join the war on the side of the western allies.

That night Duchamp, with American artist John Sloan and four friends, climbed the Washington Arch at the foot of Fifth Avenue, a Greenwich Village landmark. They took a picnic lunch, several bottles of wine, some red, white and blue balloons and a proclamation.

After drinking a certain amount of the wine and fixing the balloons to the ramparts, five of the conspirators fired off cap pistols and the sixth declaimed the proclamation. It consisted almost entirely of repetitions of the word ''whereas," a typical Dada touch, and ended with declaring Greenwich Village a free and independent state.

A little more than two months later a group of artists, with Duchamp as chairman of their board, met to consider a sculpture called Fountain, a porcelain urinal Duchamp had bought at a plumbing supplies shop. The committee voted to reject it. Duchamp and photographer Alfred Stieglitz, another member of the board, resigned in protest.

Fountain became an ancestor of conceptual art, art based on a concept; found art, objects the artist has just picked up; and ''ready-made'' art, existing objects the artist just changed a bit, like the doctored Mona Lisa. Fountain and the version of the Mona Lisa are both in the National Gallery show.

It's as if the Dadaists anticipated a quote that the Andy Warhol Foundation attributes to its founder: ''Art is what you can get away with.''

The exhibition includes work by Duchamp, Man Ray, Francis Picabia, Max Ernst, Hans Arp, Paul Klee and others who became famous for their work among the Dadaists and in other styles. They frequented a kind of salon in the ample apartment of Walter and Louise Arensberg, just off Central Park West. The couple kept a collection of modern art, now in the Philadelphia Museum of Art, and they set up a studio for Duchamp.

One of the habitues was the Baroness Elsa von Freytag-Loringhoven, wife of a German who was a war prisoner in France. She was a precursor of today's performance artists. The catalog for the show describes her as wearing a coal scuttle or wastebasket for a hat and clothes hung with things she found on the street or shoplifted from Woolworth's, including toys, gilded vegetables, tea balls, curtain rings and a battery light rigged as a bustle.

''I cannot figure out what Dadaism is,'' poet Hart Crane wrote to a friend. ''But if the baroness is to be a keystone for it, then I think I can possibly know when it is coming and how to avoid it.''

Despite the strong anti-German feeling of the time, the Arensberg group and its many German-born members got into no serious political trouble. But Duchamp might have been subject to a draft in the United States despite his physical exemption in France. He was ordered not to leave the United States without official permission, according to a recent biographer.

Duchamp gave the Philadelphia museum a three-dimensional work he had been doing in his American studio for the last 20 years of his life. It's called Given: 1. The Waterfall 2. Illuminating Gas. A large three-dimensional piece, it consists of a nude woman holding a gas lamp with a waterfall in the background.

''Dada'' will be in Washington through May 14. Admission is free. It then goes to the Museum of Modern Art in New York, May 18 to Sept. 11.

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On the Net:

National Gallery of Art: http://www.nga.gov

by Carl Hartman, Copyright 2006 Associated Press