"From our own history, we know the path to democracy is long and it's hard," Bush said in a ceremony honoring the 400th anniversary of Jamestown, America's first permanent English colony.
"There are many challenges, and there are setbacks along the way," Bush said. "Yet we can have confidence in the outcome because we've seen freedom's power to transform societies."
On his first visit to Jamestown as president, Bush soaked in the scene like a tourist — first watching a dig for artifacts, then climbing aboard a replica of a majestic ship.
He even grabbed a baton and playfully led the 400-piece orchestra before heading back home.
In his speech, Bush said the United States must stand with those struggling to gain their freedom. He spoke from the place where the country's roots began centuries ago in a swampland.
"Today, Democratic institutions are taking root in places in places where liberty was unimaginable not long ago," the president said.
He specifically cited Iraq and Afghanistan.
"The advance of freedom is the great story of our time, and new chapters are being written every day," he added.
Jamestown in 1607 was a grueling commercial venture, and colonists dealt with hunger, violence and hopelessness. But, over time, it became a starting point of representative government, free enterprise and cultural diversity.
"It is a chance to renew our commitment to help others around the world realize the great blessings of liberty," Bush told several thousand of people in the audience for the celebration.
Earlier, Bush and first lady Laura Bush walked the grounds at a leisurely place.
On a day that turned from gray to sunny, they began with a walking tour of Historic Jamestowne, where archeologists continue to unearth storied remains. The structure of the settlers' original triangular fort — long thought to have been washed way — has been recovered.
Bush marveled at a new find — a hilt basket, which is a hand guard that goes around a sword's handle. The item was discovered the day Queen Elizabeth II visited Jamestown recently and excavated on Sunday, said Mike Litterst, a spokesman for the National Park Service.
Bush then strolled through Jamestown Settlement, where early 17th century living is re-enacted. The settlement features replicas of the three ships that sailed from England to Virginia, along with recreations of the colonists' fort and an Powhatan Indian village.
The president looked at weapons and tools of the time, and watched as the sails of the replica ship he had earlier boarded, the Susan Constant, were unfurled.
Then came four ceremonial cannon blasts — so loud they made the president shudder.
Bush's speech came on the final day of the anniversary weekend, the centerpiece of an elaborate 18-month commemoration in the works for a decade.
Virginia has thrown major Jamestown celebrations every 50 years, but this one has given more recognition to three cultures — English, African and Indian — to tell a fuller story. Indians lost their land during the settlement, and Africans were eventually forced into slavery.
"Their story is a part of the story of Jamestown," Bush said. "It reminds us that the work of American democracy is to constantly renew and to extend the blessings of liberty."
The Bushes contributed items to a time capsule to be opened at the next grand celebration, in 50 years. They included a letter from them both, a gold coin and items from the queen's recent visit to the White House.
As the exit music played, Bush did not quite exit. He exuberantly led the orchestra during part of its performance of "Stars and Stripes Forever."