"Taiwan is only a small island, so we must speak out really loud to make the world hear that we are a democracy facing an evil giant," said Vivian Wang, a 38-year-old restaurant worker who traveled by bus from the southern city of Kaohsiung — about 190 miles away.
Hundreds of thousands assembled at 10 different areas in Taipei, with each route representing one of the articles of the anti-secession law. The marchers converged on the wide boulevard in front of the Presidential Office building.
Beijing is worried that self-ruled Taiwan is drifting toward independence, and China's legislature recently passed a law codifying the use of military force against Taiwan if it seeks a permanent split. The island — just 100 miles off China's southern coast — has been resisting Beijing's rule since the Communists took over the mainland in 1949.
Taiwan has been able to enjoy de facto independence for more than 50 years, largely because the United States has warned it might defend the island if China attacks. America is also the only major nation that sells advanced weapons to newly democratic Taiwan, about the size of Maryland and Delaware combined.
"What do we want from China? Peace," lawmaker Bikhim Hsiao led the crowd in chanting.
Thousands of tour buses brought protesters to Taipei from all over the island. Police estimated the crowd at about a million. The rally was organized by private groups, but leaders of President Chen Shui-bian's Democratic Progressive Party played a high-profile role in the organization.
A five-story-high white balloon representing peace, and an equally tall model of a red sea urchin, its needles symbolizing the missiles China is pointing at Taiwan, were erected at the protest site. The sea urchin model was deflated at the end of the rally, while protesters climbed over it, trying to tear it apart.
"China is a violent country. We want nothing to do with it," said Wu Chao-hsiung, a carpenter from Taipei who attended the protest. "We have to insist on the freedom to determine our own fate."
Behind her, U.S. and Japanese flags flew below a green protest banner. Many Taiwanese see those two countries as the island's most likely allies in any military conflict with China.
Chen appeared at an intersection along one of the protest routes, protected by 500 plainclothes bodyguards. Police had to push photographers out of the way to allow him to join the marchers.
Chen has long been a fierce critic of Beijing's Communist leadership and has resisted China's increasing pressure to unify.
As he promised, Chen did not speak at the rally, but mounted the stage and chanted slogans with the crowds. Critics had said that holding a speech at the event might have provoked China.
Former President Lee Teng-hui, 82, who has become a vocal supporter of independence since retiring in 2000, also marched in the protest.
Police set up barbed wire at the opposite side of the Presidential Office building to prevent protesters from turning their anger against the headquarters of the opposition Nationalist party. Leaders from the Nationalists — who oppose independence and want to improve relations with China — stayed away from the demonstration.
"Each person has his own way of opposing the anti-secession law, but in the end, Taiwan must have peace and stability," said Nationalist Party Chairman Lien Chan.
A handful of protesters ripped Chinese flags to pieces close to the building, but police prevented them from burning the flags. No major clashes were reported during the protest.
Supporters of Taiwan's cause also staged demonstrations overseas. In Hong Kong, about 100 protesters marched to oppose the anti-secession law. Taiwanese TV stations also showed footage of protests in Los Angeles and Brussels, Belgium.
Joseph Wu, a Cabinet official in charge of China policy, said the protest would force Beijing to change its attitude. "Beijing understands the anti-secession law has caused an international uproar," he said. "Now we'll have to wait and see what they do to remedy the damage."