Thousands gathered to wish "bon voyage" to the painstakingly recreated tall ship Hermione, leaving from Ile d'Aix, in southwest France, for the east coast of the United States.
The French and American flags were raised on the wooden frigate as it embarked on an Atlantic crossing retracing the voyage 235 years ago of General Lafayette, who won fame for rallying America's rebels fighting for independence from Britain.
US consul in Bordeaux Thomas Wolf read out a statement in French from President Barack Obama in which the American leader spoke of the "unwavering friendship and solidarity between the two countries".
"The tribute we are paying today to the extraordinary efforts by General Lafayette and the French people in favour of the American Revolution reminds us that our partnership with France has made it the oldest ally of our nation," he added.
Some 80 crew members will sail the three-masted 213-feet ship along the route to Boston made by French General Gilbert du Motier - the Marquis de Lafayette - to bolster revolutionaries fighting for an independent United States.