Critics tend to discount political advocacy when it is inspired by sexual desire. Jean Genet’s support of causes ranging from Arab rights to black power has been ascribed to that writer’s libido, while E. M. Forster’s objections to the abuses of colonialism were recently discounted in the Literary Review by V.S. Naipaul, who in 2001 called Forster a “nasty homosexual” whose only interest during his passages to India was procuring “garden boys.” Never mind that the timid, tiny Forster was in fact enamored of a strapping Alexandrian tram conductor — his motives were dubious in the eyes of Naipaul. The British writer and political activist Nancy Cunard (1896–1965) edited and self-published a path-breaking anthology, “Negro” (1934), while involved in a love affair with a black jazz pianist, Henry Crowder (1890–1955). Yet as explained in a new biography, “Nancy Cunard: Heiress, Muse, Political Idealist” by Lois Gordon (Columbia University Press, 447 pages, $32.50), Cunard’s powerful idealism in the civil rights movement found only a relatively unsatisfactory echo in her actual love life.

Cunard’s “Negro” is a massive 855 page assault of a book, with contributions from some 150 writers, including Langston Hughes, Zora Neale Hurston, and William Carlos Williams. Samuel Beckett’s translations of the French contributions to the book are noteworthy enough to have been gathered into “Beckett in Black and Red: The Translations for Nancy Cunard’s ‘Negro'” (University Press of Kentucky, 288 pages, $34.95). Cunard’s book teems with an energetic generosity that seems extinct in the publishing world today — a severely abridged 464 page version of “Negro” from Continuum Publishing is all that remains in print. Cunard’s radical message, that Africa is “in the iron grip of its several imperialist oppressions…The white man is killing Africa” hardly convinced her paramour Crowder. Indeed, Crowder objected that he himself was not an activist and he later published a book calling himself a “pawn upon her chessboard of life.”

Cunard’s adamant concern for the oppression suffered by blacks was real, despite her unlikely appearance as a skeletal wraith, typically overdressed in clunky arm bracelets and caked with makeup. An heiress to the Cunard shipping line fortune, Cunard was partially disinherited by her racist mother, who was horrified by her daughter’s social life, but still wanted her to look fashionably attired in the inevitable press photos. “Negro” included reports of lynchings and accounts of the notorious case of the Scottsboro boys, nine black teenagers in Alabama falsely accused of raping two white women. Cunard even included some of the hate mail that she had received. One letter called her a “dirty lowdown betraying piece of mucus.” The wildly varying tone and content of “Negro” made it a surrealist construction akin to André Breton’s “Anthologie de l’humour noir” (1940), and not by coincidence, another of Cunard’s many lovers was the French surrealist poet Louis Aragon.

Ms. Gordon, a professor of English at Fairleigh Dickinson University, is a faithful narrator of Cunard’s failed historical struggles on the Republican side during the Spanish Civil War, and against the rising tide of fascism in Europe. On cultural issues, Ms. Gordon is less comfortable than Anne Chisholm, whose fluent “Nancy Cunard: A Biography” (1981) is still available from Penguin Books and well worth hunting down. Ms. Gordon refers to “Heraclitis,” “Anatol France,” and a friend’s threat to “disinherit Nancy from the Manet painting she had loved since childhood.” Surely Heraclitus and Anatole France would agree that someone can be disinherited from a family or a will, but never from a painting. All the personalities here — however homely in real life — are described as physically attractive with cloying, wearying enthusiasm. According to Ms. Gordon, the homely William Carlos Williams was “good-looking,” the mousy novelist Michael Arlen was “exotically handsome,” blind and gawky Aldous Huxley was “handsome,” and even the curvaceously plump artists’ model Kiki de Montparnasse is termed “lean.” More problematic are references to “the Nancy characters” supposedly inspired by Cunard in her friends’ plays and novels, which betrays a lack of understanding of the difference between fiction — even in the genre of roman à clef — and history.

An even more basic misunderstanding is the persistent characterization of Cunard’s limp, numb doggerel as poetry of interest and talent. By contrast, her vigorous prose, including colorful memoirs of the writers Norman Douglas and George Moore, are comparatively neglected. A detailed look at Cunard’s “Grand Man: Memories of Norman Douglas” (1954), particularly overdue for reprint, would have brightened up the account of Cunard’s later years, which were otherwise occupied with drink, physical illness, and episodes of lunacy. A feisty, intemperate polemicist of rare uncompromising strength, Cunard left a rich legacy of courage based in love. She told one African-American friend who was grateful for her generosity: “I am your mother. There is no payment due.” Today’s readers may conclude that the debt owed by posterity to Nancy Cunard still remains to be paid out in full.

Mr. Ivry last wrote for these pages on Bach.