You may recall the to-do occasioned two winters past by a certain shift in the mise-en-scène at the United Nations. New blue drapes appeared to conceal the grisaille tapestry hung in the corridor outside the Security Council chamber in which then-Secretary of State Colin Powell had come to make the case for war against Iraq, and where the secretary was scheduled to hold a press conference. Some newspapers reported that Powell’s staff demanded that the offending artwork be concealed. The Internet was aflame; some weeks later The Weekly Standard attempted damage control by explaining that TV crews had only requested that a distractingly busy backdrop be simplified.

The latter was closer to the truth. Powell would have shared the screen with a horse’s rear. Still, Pablo Picasso’s Guernica was back in circulation–and not just as the tapestry that, unable to purchase the thing itself, Nelson Rockefeller commissioned and his widow donated to the UN. Guernica‘s shrieking horse, dead children and terrorized wraiths were held aloft on placards at antiwar demonstrations in the streets of New York and plastered across a Hollywood Boulevard billboard. Sophie Matisse, great-granddaughter of the French painter, exhibited her colorized appropriation of Picasso’s most famous painting–inspired, she explained, by the destruction of the twin towers. As war approached, The New Yorker and Harper’s had a public spat over which first had the idea to emblazon its cover with the image that Gijs van Hensbergen considers the modern equivalent of the Crucifixion.

Hensbergen’s “biography” is the eleventh book (in English) devoted to Picasso’s mural. As such, it’s more interested in the work’s career than its quality, less concerned with Guernica‘s iconography than with its iconic status. For, something heavier than a painting, Guernica symbolizes both the horror of war and the idea that a masterpiece might have a political significance; it promotes the hope that modern art could even be progressive. At the same time, however, Guernica represents something recently demonstrated in this year’s passionate torrent of anti-Bush agitprop, namely art’s ineffectuality in the production of concrete political results. Ubiquitous and universal, an antifascist altarpiece that even a fascist might covet, Guernica–as Andy Warhol once said of the Empire State Building–is a star.

Is Guernica defined by a specific historical moment or by the artist’s personal mythology? In January 1937 Picasso–already producing satiric anti-Franco graphics to benefit the beleaguered Spanish Republic–was commissioned to provide a mural for the Spanish pavilion at the upcoming Paris International Exposition. Whatever his original idea may have been, it was obliterated on the afternoon of April 26, when the German Luftwaffe reduced the Basque city of Gernika to rubble. This aerial attack, which lasted only three hours, was unprecedented in Europe. It was intended as a demonstration and, thanks largely to the dispatches filed by British war correspondent George Lowther Steer, became instantly synonymous with the mass destruction of innocent civilians–an exposition before the Exposition, a little twentieth-century horror presaging the inconceivable ones of Auschwitz and Hiroshima.

Five days later, Picasso began to develop his ideas, drawing on the specific imagery–the ritual of the corrida, the myth of the minotaur, images of Christian martyrdom and suffering women–that had characterized his work for the past half-dozen years. Sketches and preparatory paintings poured forth: the artist as force of nature. Picasso’s lover Dora Maar made a photographic record of the process; Paul Eluard, working on his poem “The Victory of Guernica,” visited the studio frequently during those weeks. At one with the zeitgeist, Picasso wasn’t the only painter to take this subject–or even perhaps the first. René Magritte painted Le Drapeau Noir, a dark-blue sky filled with enigmatic flying machines. Two artists in far-off New York, Philip Guston and the social surrealist Anton Refregier, executed canvases inspired by the fate of the Basque city. Picasso began painting his in June, completing the 275-square-foot mural in time for the International Exposition in July.

Anarchists and POUMistas were being liquidated in Barcelona; the Stalinist terror had resumed in Moscow. Boris Iofán’s monumental Soviet pavilion faced Albert Speer’s even taller German pavilion, the Nazi eagle peering down on Vera Mujina’s forward-striding Worker and Collective Farm Woman. Overshadowed by its totalitarian neighbors, the Spanish pavilion was nevertheless characterized by an ambitious, coordinated statement on the Civil War–involving posters, graphic displays and documentary films. Grenade in hand, José Antonio’s rough-hewn and resolute bronze Soldier stood guard outside; within, Picasso evoked the suffering of the civilian population.

Thanks in part to its near-monochromatic palette, Guernica had the authority of a photograph. The initial reception to the mural was, according to Hensbergen, “strangely muted.” Spanish officials were disappointed that Guernica wasn’t more partisan, and the Basques, in particular, were displeased by the artist’s subjectivity. Years later Rudolf Arnheim would observe, Guernica was not based on a “dualistic antagonism.” The aggressors were invisible. Not a political statement but an illustration of existential terror, the mural “depicts the effects of a brutality that strikes from nowhere.” But weren’t these tortured, distorted bodies the result of applied fascism?

Then Guernica went on tour. The mural was exhibited throughout Scandinavia, arriving in London on September 30, 1938, the very day of the Munich Pact between Hitler and British Prime Minister Neville Chamberlain. Guernica served as a fundraiser in England and the United States before making its formal debut as the centerpiece of the Museum of Modern Art’s Picasso retrospective, which opened six weeks after the Nazi invasion of Poland. In that context, the mural was not just an antifascist statement but a prime chunk of European Modernism that had found refuge in America. The curator James Thrall Soby declared Guernica “the most forceful achievement of our century.” Here, pace Adorno, was poetry after Auschwitz before Auschwitz.

Meanwhile, New York was gripped with Picasso-mania. Some 60,000 visitors jammed MoMA; the window displays at nearby Bonwit Teller and Bergdorf Goodman were inspired by Picasso. Hensbergen is even more emphatic in detailing the impact that Guernica had on local painters. Arshile Gorky, the town’s leading picasseño, was devastated; Guernica summoned up the Armenian genocide, which he had witnessed as a child. For seekers of the timeless and tragic like Adolph Gottlieb, Mark Rothko and Barnett Newman, Guernica was, Hensbergen says, “a totem to the idea of the sublime.”

De Kooning, whose native Rotterdam would soon be destroyed by the Luftwaffe, was stunned by the implications of Picasso’s fractured space and bravura “wrap-around picture”–and what is Robert Motherwell’s ongoing series Elegies for the Spanish Republic if not a two-decade-long response to Guernica. It “floored me,” Lee Krasner recalled. Even more than Gorky, Jackson Pollock took on Guernica, analyzed it and moved beyond it. (It was Pollock’s One that replaced Guernica in MoMA’s permanent exhibition.)

While New York painters pondered Guernica‘s scale and grappled with its pictorial implications, Picasso himself became increasingly political. The artist joined the Communist Party in 1944; as the war ended, he executed a second “Guernica,” the large grisaille Charnel House; in January 1951 he would produce a third one, Massacre in Korea. Unlike Guernica, Massacre in Korea presents robot death soldiers as well as their naked victims. (Hensbergen calls it “the one canvas that you wish Picasso had never painted.”) More popular was the dove that the artist featured on a poster designed for the Communist-organized Paris Peace Congress in April 1949.

What sort of political figure did Picasso cut? An August 1937 editorial in the New Masses had called attention to the artist’s bold antifascism; the Communist journal would soon hail him as “the greatest painter of modern times.” But a long interview in the New Masses‘ March 1945 issue, dealing in part with Picasso’s political commitment, prompted illustrator and Stalin sympathizer Rockwell Kent to dismiss Picasso’s recent work as “just plain silly” and “without a single redeeming feature.” Nor was Kent the only true believer to attack the world’s leading celebrity Communist. In a bellicose 1947 defense of the new Soviet art, Pravda singled out Matisse and Picasso as decadent formalists. The same year, the critic Vladimir Kemenov went further, attacking even the culminating expression of universal antifascism: “The images of Guernica are as monstrous and pathological as in Picasso’s other paintings…. The aim of Picasso’s morbid, repulsive works is not to criticize the contradictions of reality, but to make an aesthetic apology for capitalism.”

Capitalist diva or ambassador of peace, Guernica went back on the road after the Korean War. The painting was the centerpiece of Italy’s first Picasso retrospective; it traveled on to Brazil and toured Europe throughout 1955 and early 1956. Guernica was exhibited in Munich, Cologne, Hamburg, Brussels, Amsterdam and Stockholm, returning in triumph for Picasso’s 75th birthday to New York, where it was installed in the third-floor gallery at MoMA. Even the Soviets began to relax. By 1971 Leonid Brezhnev was free to pose before a Picasso canvas.

No less than Picasso’s dove, his mural became an emblem of the international peace movement. Effacing Guernica‘s antifascist past and perhaps inoculating it against charges of Communist propaganda, MoMA felt compelled to place a panel denying that the painting had any political significance beyond the artist’s “abhorrence of war and brutality.” Alain Resnais’s 1950 collage-film Guernica populated the destroyed Basque city with Picassoid ghosts, accompanied by Spanish actress María Casares’s reading of Eluard’s poem and Guy Bernard’s spare, solemn score. More than any contemporary painter, Resnais is Guernica‘s aesthetic heir. His short appreciation would provide the template for subsequent essays in highly formalist Protest Modernism: Night and Fog, Hiroshima Mon Amour and Muriel. (The frenzied pyre of war footage, staged and actual, that opens Jean-Luc Godard’s new film Notre Musique might be seen as another example of guernicaisme.)

Given the toll taken by four years of travel, Guernica, Picasso decided, would remain in New York until its final transport to Spain, following the death or (less likely) the fall of Francisco Franco. The painting scarcely had to tour, however, to be incorporated into the protest rhetoric of the Vietnam War. Numerous posters appropriated Guernica as an image, particularly after the late 1969 revelation of the My Lai massacre. MoMA’s third floor was the unwilling host to occasional antiwar vigils. Several antiwar groups contacted Picasso and requested he withdraw his painting from MoMA. After consulting with his dealer Daniel-Henry Kahnweiler, however, Picasso decided that the once-again relevant painting should stay. “The truth of the matter is that by means of Guernica I have the pleasure of making a political statement every day in the middle of New York City,” he told his friend, the poet Rafael Alberti.

As early as 1967 the activist painter Leon Golub warned a symposium on the art of social protest that Guernica risked overexposure. To judge from Hensbergen’s book, it certainly seems difficult to say anything new about the painting as painting. In early 1974, less than a year after Picasso’s death, the future art-dealer Tony Shafrazi attempted to redeem the cliché. Ostensibly protesting Nixon’s pardon of My Lai massacre culprit William Calley and in imitation of the graffiti artists he would champion, Shafrazi defaced Guernica with–easily removable–red spray paint: KILL LIES ALL.

Nor was Shafrazi’s the only desecration. Peter Saul’s 1973 canvas Liddul Guernica represents Picasso’s painting as a construction in udders and inflated latex, with handy labels affixed: “sensubble arrt,” “bewtiffle arrt,” “expweshun issum,” “dah-dah izzum,” “foney coobeezm.” The shrieking central figure, leaning out a window, none other than “Paablow.” Saul recognized that, whatever its original intention, Guernica was Pop. (In 1974 Art Spiegelman quoted Guernica in his most ambitious graphic story before Maus, “Ace Hole, Midget Detective.” What’s remarkable is how well Picasso’s image anticipates the distortions of the cartoon universe.)

In Franco’s Spain, however, one might be jailed merely for receiving a Guernica postcard through the mail. This did not prevent much discussion, recounted by Hensbergen, on the nature of the painting’s eventual disposition. Should it reside in the Prado, per Picasso’s wishes, or perhaps go to Madrid’s newly planned Museo de Art Contemporáneo? Sensubble or bewtiffle? Even Franco was involved in the maneuvering to appropriately place this national treasure. The dictator died in 1975, and the war was over.

Six years later, Guernica arrived in Spain–a source of prestige and much ancillary merchandise. Hensbergen, who refurbishes Guernica‘s aura the way another might restore the canvas itself, notes without particular irony that even the wooden crate that had protected Guernica in its voyage across the Atlantic was preserved and put on display as a holy relic.