VENTOTENE, Italy — The leaders of Italy, France, and Germany vowed Monday to improve Europe's defense and economic prospects as they paid tribute to one of the founding fathers of European unity in a symbolic bid to relaunch the European Union after Britain's vote to leave.
Standing silently together, Prime Minister Matteo Renzi of Italy, Chancellor Angela Merkel of Germany, and President Francois Holland of France placed three bouquets of blue and yellow flowers — the colors of the European Union — on the white marble tombstone of Altiero Spinelli on the island of Ventotene.
Spinelli, along with another intellectual confined to Ventotene in the 1940s by Italy's fascist rulers, co-wrote the ''Ventotene Manifesto'' calling for a federation of European states to counter the nationalism that had led Europe to war.
The document is considered the inspiration for European federalism.
Renzi invited his French and German counterparts to the sun-soaked island off Naples to remind Europe of its founding ideals as the European Union forges ahead amid a spate of challenges, from slow economic growth to Islamic extremist violence, after Britain's vote to leave the bloc.
''Many people thought that after Brexit, that Europe was finished. It's not like that,'' Renzi said after the hour-long summit. ''We respect the choice of Britain's citizens, but we want to write a page for the future.''