PORT-AU-PRINCE, Haiti, Jan. 1 ? Two hundred years ago, an army of African slaves defeated French forces on this tropical island, ending Napoleon’s ambition to dominate the Americas and paving the way for the first black republic.

On Thursday, President Jean-Bertrand Aristide led a tense and chaotic observance of that bicentennial, though many found little to celebrate in Mr. Aristide’s governance over what, after 200 years of independence, remains an impoverished and troubled nation.

Speaking to a small but enthusiastic crowd, Mr. Aristide called Haiti “the mother of liberty,” and appealed to opposition groups, which have mounted ever larger demonstrations against his government, to agree to new elections this year.

“Civil society, the poor, the rich, the opposition, everybody, must come together to heal Haiti,” Mr. Aristide said to the cheering crowd, which filled a city block and rows of bleachers set up in front of the white presidential palace in the center of the city.

The crowd, many of them poor and unemployed Haitians who spent New Year’s Eve on the street waiting for the celebration, climbed atop a spiked green metal fence meant to keep them out of the palace, toppling it and injuring several people.

The throng rushed onto temporary risers set up for spectators on the palace lawn, but the risers, so new they still smelled of freshly sawed pine, also collapsed, sending the crowd rushing further still toward the dignitaries on the dais in front of the palace.

Policemen with submachine guns strained to hold back the crowd, which surged forward and chanted “Aristide or death!” The president then delivered his speech, outlining a 21-point program that he said would lift Haiti from poverty and political discord by 2015. That plan remains contingent on a $21 billion payment he is seeking from France as reparation for the payment Haiti was forced to make to France when it won its independence.

But across the capital, many Haitians were in no mood to celebrate or listen to plans for the future. Two-thirds of the country’s workers are unemployed, and most Haitians live on about $1 a day. Haiti is the poorest nation in the hemisphere and leads the region in the number of AIDS cases. Life expectancy is little more than 50 years.

Since 2000, when Mr. Aristide was re-elected to the presidency in voting that many observers said was flawed, the country has been locked in political crisis. The dispute led international donors to suspend $500 million in aid, adding to the country’s economic woes.

The political battle intensified when opposition groups boycotted parliamentary elections, leading to a sweep by pro-Aristide politicians. The current Parliament’s term ends this month, and if a new one is not elected, the country will be plunged into still deeper disarray.

“Today we were supposed to celebrate, but instead it is a day of mourning,” said Bernadel Romel, who stood among thousands of demonstrators who had planned to march to the statue of Jean-Jacques Dessalines, the former slave who led the country immediately after its independence, across the street from the palace.

Their path was blocked miles from the palace by policemen in riot gear and gas masks, who fired tear gas at the demonstrators.

“We thought Aristide would bring freedom,” Mr. Romel said. “Instead he brought only death and tyranny.”

Mr. Aristede had invited heads of state from around the globe for what was planned as a lavish celebration. But it was a measure of Mr. Aristide’s political isolation and Haiti’s persistent troubles that only one showed up.

The head of state who did attend, President Thabo Mbeki of South Africa, brought a security guard of more than 50 people, along with ambulances, an armored car and two helicopters. The only other government leader present was the prime minister of the Bahamas.

The turnout hardly provided the opportunity to rally support among an increasingly agitated public that Mr. Aristide had hoped for in commemorating the stunning defeat that a rebel army of former slaves dealt to Napoleon’s forces, led by the emperor’s brother-in-law, Gen. Charles Leclerc.

That defeat so rattled Napoleon that he promptly gave up his American colonial ambitions, selling the Louisiana Territory to the United States. But their victory over the French failed to bring immediate or lasting freedom to Haiti’s people.

For a century they struggled under a series of tyrannical and ineffective leaders. Revolutions came and went with dizzying speed. Between 1843 and 1889, 14 leaders were assassinated or overthrown. This tumultuous history led President Rosalvo Bobo to remark on Haiti’s centennial that he hoped the next 100 years would bring better days.

But much of the 20th century matched the previous one. Chaos and tyranny reigned, culminating in the brutal dictatorships of François Duvalier, and his son, Jean-Claude, who fled the country in 1986.

When Mr. Aristide, a former priest who pledged his allegiance to Haiti’s poor, was elected president in 1990, his ascendancy seemed a sign that Haiti’s history of rapacious dictators had come to an end. But he was quickly ousted in a coup, then reinstated in 1994 by American troops.

A decade later, there are a few signs that life has improved for the vast majority of Haitians.

“Aristide has been in power since 1994, and nothing has changed,” said a leading businessman who is active in the movement to remove the president, but who asked that his name not be used because he feared reprisals. “The people are still poor and oppressed. We are told to celebrate our liberty but we don’t feel free.”

At a news conference on Wednesday, Mr. Aristide disputed such criticism, saying he welcomed the opposition groups as an essential part of the country’s future. He said he hoped to hold parliamentary elections this year and urged the opposition parties to support his plan.

“The opposition are not enemies,” Mr. Aristide said. “They are playing a role in democratic society.”

But protests in the streets of Port-au-Prince and other cities have grown in recent months, and become increasingly tense and sometimes violent. On Dec. 5, Aristide supporters stormed the national university, a hotbed of anti-Aristide activism, beating about 20 people who opposed the Aristide government.

Outraged by the violence, civic groups, trade unions and professional associations rallied to the opposition movement, swelling the ranks of demonstrators.

Opposition groups said dozens of people have been killed and scores have been wounded in clashes with armed groups of Aristide supporters while the police either stand by or participate.

In Gonaïves, the coastal city where Haiti’s independence was proclaimed and a flashpoint of the current political struggle, militants once loyal to Mr. Aristide have since turned against him, engaging in gun battles in the streets.

On Wednesday, as crews worked to complete the stage upon which Mr. Aristide was to speak in Gonaïves on Thursday, people in Raboteau, one of the city’s slums, warned the president to stay away.

“If Aristide comes here I am going to handcuff him and I am going to kill him,” said a 19-year-old member of a militia once loyal to Mr. Aristide known as the Cannibal Army. The young man, Bristey Metayer, waved a pair of handcuffs and warned a visitor: “Don’t come to the celebration tomorrow. There will be blood.”