Madame Chiang Kai-shek, a pivotal figure in one of the 20th century's great epics — the struggle for control of post-imperial China waged between the Nationalists and the Communists during the Japanese invasion and the violent aftermath of World War II — died on Thursday in Manhattan, the Foreign Ministry of Taiwan reported yesterday. She was 105.

Madame Chiang, a dazzling and imperious politician, wielded immense influence in Nationalist China, but she and her husband were eventually forced by the Communist victory into exile in Taiwan, where she presided as the grande dame of Nationalist politics for many years. After Chiang Kai-shek died in 1975, she retreated to New York City, where she spent the rest of her life.

But her old influence overseas was matched, and perhaps exceeded, by the relentless and sophisticated lobbying effort she and her husband set up in Washington, through which they distributed uncounted millions through law firms and public relations companies to promote Taiwan's cause and maintain recognition by the American government.

During the 1950's, Madame Chiang and her husband blamed the United States for the Nationalists' loss of China, and continued to campaign for help from Washington to retake the mainland. Although that hope eventually faded, American support for Taiwan remained strong for years, delaying Washington's recognition of Beijing as the capital of China until 1979, three decades after the Communists seized power.

As a fluent English speaker, as a Christian, as a model of what many Americans hoped China to become, Madame Chiang struck a chord with American audiences as she traveled across the country, starting in the 1930's, raising money and lobbying for support of her husband's government. She seemed to many Americans to be the very symbol of the modern, educated, pro-American China they yearned to see emerge — even as many Chinese dismissed her as a corrupt, power-hungry symbol of the past they wanted to escape.

Ultimately, that difference in perspectives was perhaps one reason that she fled an increasingly democratic Taiwan, where many people reviled her and where she felt less at home as native Taiwanese eclipsed the exiled mainlanders.

Madame Chiang was the most famous member of one of modern China's most remarkable families, the Soongs, who dominated Chinese politics and finance in the first half of the 20th century. Yet in China it was her American background and style that distinguished Soong Mei-ling; that was her maiden name, sometimes spelled May-ling.

For many Americans, her finest moment came in 1943, when she barnstormed the United States in search of support for the Nationalist cause against Japan, winning donations from countless Americans who were mesmerized by her passion, determination and striking good looks. Her address to a joint meeting of Congress electrified Washington, winning billions of dollars in aid.

She helped create American policy toward China during the war years, running the Nationalist government's propaganda operation and emerging as its most important diplomat. Yet she was also deeply involved in the endless maneuverings of her husband, who was uneasily at the helm of several shifting alliances with Chinese warlords vying for control of what was then a badly fractured nation.

A devout Christian, Madame Chiang spoke fluent English tinted with the Southern accent she acquired as a schoolgirl in Georgia, and she presented a civilized and humane image of a courageous China battling Japanese invasion and Communist subversion. Yet historians have documented the murderous path that Chiang Kai-shek led in his efforts to win, then keep, and ultimately lose power. It also became clear in later years that the Chiang family had pocketed hundreds of millions of dollars of American aid intended for the war.

Madame Chiang had a notoriously tempestuous relationship with her husband, and then with his son by a previous marriage, Chiang Ching-kuo, who became Taiwan's leader after Chiang Kai-shek's death. She had no children.

Her skill as a politician, alternately charming and vicious, made her a formidable presence. She made a play for Taiwan's leadership after Chiang Ching-kuo died in 1988, even though she was 90 and living in New York.

Although she suffered numerous ailments, including breast cancer, she outlived all her contemporary rivals. She was said to credit her religious faith — she told friends she rose at dawn for an hour of prayer each day — for her good health.

Gen. Joseph W. Stilwell, who worked closely with her when he commanded American forces in China during the war, described Madame Chiang in his diary as a "clever, brainy woman."

"Direct, forceful, energetic," he wrote. "Loves power, eats up publicity and flattery, pretty weak on her history. Can turn on charm at will and knows it."

Soong Mei-ling's rise to power began when she married Chiang in an opulent ceremony in Shanghai in 1927, bringing together China's star military man with one of the nation's most illustrious families.

Her eldest sister, Soong Ai-ling, directed the family's affairs and innumerable money-making ventures with the help of her husband, H. H. Kung, a scion of one of China's wealthiest banking families.