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President Bush paid tribute to former slaves Tuesday, visiting Senegal (search)'s "point of no return" for many Africans bound for early America's shores.

Bush then boarded Air Force One (search) for South Africa, the next stop in his five-day, five-nation African tour.

Bush toured Goree Island (search), the site of the port, with Mrs. Bush, Senegalese President Abdoulaye Wade and his wife. The president spoke in grim and impassioned terms about the history of slavery in America, calling it "one of the greatest crimes of history."

He stopped short of formally apologizing for America's role in supporting the slave trade.

Bush visited a slave house built by the Dutch in 1776 and held in his hands some of the same chains that once shackled some 200 human beings per day at their last stop before heading out on their often murderous journey to the Americas.

Bush called the house "very moving, very touching" and said it "reminds us never to forget history."

"Human beings delivered, sorted, weighed, branded with marks of commercial enterprises and loaded as cargo on a voyage without return," Bush said. "One of the largest migrations in history was also one of the greatest crimes of history."

In his speech, Bush said African-born slaves utlimately helped to set America free by awakening a collective conscience. The slaves achieved that by never surrendering their spirit even as the spirit of their captors became corrupted.

"Small men took on the powers and airs of tyrants and masters. Years of unpunished brutality and bullying and rape produced a dullness and hardness of conscience. Christian men and women became blind to the clearest commands of their faith and added hypocrisy to injustice. A republic founded on equality for all became a prison for millions," Bush said.

Despite painful shared history, Bush said the United States and African nations must work together to eradicate disease and war, and to encourage greater business ties.

"We know that these challenges can be overcome because history moves in the direction of justice," Bush said.

Bush arrived Tuesday morning in Senegal -- one of West Africa's oldest and most stable democracies -- the first stop on a tour aimed at bringing a hopeful and democratic future to the continent.

The president views Wade as one of his most reliable supporters in the war on terror and was greeted by the Senegalese president and a full-scale military arrival ceremony.

Wade said African nations need help building their economies so they can overcome slavery's legacy. Bush's idea for a Millennium Challenge Account (search)  would give money to countries who promise to move toward democracies and who help quash terrorism.

"All Africans are asking for is infrastructure so Africans can work," Wade said, specifically requesting "heavy military equipment" to help with farming.

After a private meeting, Bush and Wade met with their West African democratic counterparts: President John Kufuor of Ghana, Mathieu Kerekou of Benin, Pedro Pires of Cape Verde, Yahya Jammeh of Gambia, Amadou Toumani Toure of Mali, Mamadou Tandja of Niger and Ahmad Tejan Kabbah of Sierra Leone.

Clusters of curious onlookers gathered on dirt roads to watch Bush's motorcade pass by, many standing with their arms folded across their chests, some clapping and waving.

The emotional highlight of Bush's daylong visit to Senegal was the boat ride to Goree Island. Bush and his wife, Laura, made the trip in Wade's presidential yacht.

Still Mulling Liberia

A country not on the president's travel itinerary: Liberia (search). The Bush administration is contemplating whether to send U.S. troops to help supervise an end to the carnage there.

Bush said the group in Dakar had "a good discussion" on Liberia. Among the leaders was Kufuor, the head of the 15-country Economic Community of West African States (search)  (ECOWAS), which has been deeply involved in talks over how to stabilize Liberia.

Bush said he told Kufuor that the United States would work with that governing body on the Liberia issue and making sure President Charles Taylor (search) steps down.

"Charles Taylor must leave," Bush stressed. "The United Nations is going to be involved … the leaders of ECOWAS were at the table, all of whom are concerned about Liberia, as are we, and are concerned about a peaceful Western Africa."

When asked if the United States would commit peacekeeping troops to the region, Bush said, "We're in the process of determining what is necessary to maintain the cease-fire and to allow for a peaceful transfer of power."

Taylor says he is considering asylum in Nigeria, but apparently wants to see U.S. peacekeepers arrive before he leaves.

Bush has sent a U.S. military team to the capital city of Monrovia to assess the humanitarian situation before making a decision on whether to commit troops.

Nearly one-third of Liberia's 3 million people have been forced from their homes by fighting since rebels took up arms against Taylor in 1999. The three years of fighting are the latest round in an on-and-off insurrection that Taylor, then a warlord, started in 1989. Taylor is also wanted in neighboring Sierra Leone for backing rebels there who committed atrocities against civilians.

Bush's five-day trip to Africa, his first to the continent as president, also takes him to Botswana, Uganda and Nigeria.

Bush chose his itinerary to represent the new Africa he hopes will emerge.

The leaders of South Africa, Nigeria and Senegal want Western assistance for a plan they have formulated to rescue Africa; Botswana, a prosperous southern African nation, is actively confronting the AIDS scourge. Uganda, a thriving east African power, is seen as an important ally in confronting potential terror networks in the region.

The visit is Bush's third to Africa, but his first as president. Only three other U.S. presidents have been to the region.

Many African leaders see Bush's visit as a key part of a strategy to combat rising anti-American sentiment and the image of Washington as an international bully.

Bush's decision to attack Iraq was roundly criticized in Africa, partly because of large Muslim populations in some countries, but also because America sidelined the United Nations. The United Nations is virtually the only stage for the continent to exert international influence.

Fox News' James Rosen and the Associated Press contributed to this report.