The Nobel peace prize comes at a testing time for the European Union which has brought the continent peace and democracy for over half a century but is struggling to weather the euro debt crisis.
"It is an honour that should have come a long time ago," said Jean-Dominique Guiliani, head of the Robert Schuman Foundation, set up to honour the French politician who drove the first steps towards the EU more than 60 years ago.
Long-time adversaries France and the then West Germany agreed in 1950 to put their coal and steel industries under a single authority to show, in Schuman's words, "that a war between France and Germany becomes not only unthinkable but materially impossible."
The European project "calmed a continent scarred by wars whose horrors culminated in the 20th Century with ... two world wars among the most terrible of them all," Guiliani said.
In announcing the prize, the Nobel committee highlighted the EU's role in bringing peace after World War II left the continent prostrate and seemingly without a future as the United States and the Soviet Union faced off in the Cold War.
The EU and its predecessors "have over six decades contributed to peace and reconciliation, democracy and human rights," Nobel Committee president Thorbjoern Jagland said.
More than 60 years later, the 27 nations now in the bloc have never known such a long period of peace in a continent whose history is checkered with some of the bloodiest and most awful conflicts known to man.
Initially six -- Belgium, France, Germany, Italy, Luxembourg and the Netherlands -- the EU totalled 15 members in 2004 when it embraced the first of the former Soviet states stranded for half a century behind the Iron Curtain.
In the euphoria of the times, border posts were put into mothballs in the 1990s under the Schengen treaty allowing free travel and the single euro currency was launched the same decade.
The dream since has been dented as the stinging austerity programmes adopted to combat the eurozone debt crisis undercut support for further centralisation in a European super-state headquartered in Brussels.
While the bloc's 500 million people continue to enjoy prosperity equalled only in the United States, the power of emerging giants such as China, India and Brazil have heightened fears of decline across a continent slumping into recession and hit by soaring unemployment, especially among the young.
Resentment at the diktats laid down by Brussels to curb spending and enforce fiscal discipline has driven a backlash in the shape of mounting nationalist feeling, evident from Catalonia in Spain, to Italy, to Belgium to Scotland.
Further enlargement of the bloc appears improbable, with Turkey's long-running bid for membership increasingly seen as a pipe-dream, and the EU needing to put its own house in order first.