In the mid-1980s Giulio Andreotti, the late Italian prime minister, remarked that he liked Germany so much that he was glad there were two of them. It was an unworthy sentiment shared among other western European leaders of that era, notably Margaret Thatcher of the UK. On Saturday Germany celebrates the 25th anniversary of its reunification, and only a fool or a misanthrope would refuse congratulations to the German people.

On moral, historical and political counts, reunification has been a resounding, though not totally unqualified, success. It has brought democratic rights, civic dignity and higher living standards to the people of eastern Germany, who had known nothing since the 1930s but terror and war under the Nazis and ideologically enforced incarceration under communism. The highest representatives of today’s united state — Angela Merkel, the chancellor, and Joachim Gauck, the president — are from the east. Each commands international respect.

Reunification has also demonstrated, for the first time in modern European history, that a united Germany is not a military threat to world peace. From its birth in 1871 after the Franco-Prussian war to its death in the rubble of Berlin in 1945, this is precisely what had damned earlier incarnations of the German state.

Germany is an exemplary democracy with a sturdy, federal system of government and a commitment to a peaceful international order. Unlike Austria, France or Sweden, Germany has no rightwing populist movement of any significance. Nothing better illustrates Germany’s restoration to the front rank of nations than the fact that, seven decades after the Holocaust, it boasts one of the world’s fastest-growing Jewish communities.

Modern Germans display a confidence about their national identity that marks a departure from the guilt, self-hatred and anxiety of the first post-Nazi generations. This confidence has enabled Germany to embrace globalisation and evolve into such a diverse society that Christian Wulff, Mr Gauck’s predecessor, observed in 2010 that “Islam is now a part of Germany”.

All these achievements have come at a certain price. Notwithstanding the welcome that Germany has extended to hundreds of thousands of Syrian, Afghan and other refugees, the number of arson attacks and lesser criminal offences against asylum shelters has doubled so far this year to 437, from about 200 in the whole of 2014. The harmonious integration of immigrants poses a constant challenge.

Germany’s pacifist culture and rather provincial habits of mind translate into a diffidence on the world stage that belies the nation’s economic weight and falls short of its partners’ expectations on security issues. It is disturbing that, according to a Pew Research Center study in June, 58 per cent of Germans would oppose using military force to assist a Nato ally attacked by Russia, and only 38 per cent would support it. Germany’s handling of the eurozone crisis has also at times been short-sighted, putting so much emphasis on strict fiscal rules and its own model of export-driven growth that disunion and instability still plague the 19-nation area.

Any complaints about the quality of German leadership need to be balanced against the recognition that its major European partners are failing to rise to their own responsibilities. France and Italy are chronic economic underperformers. The UK stands on the sidelines of too many European discussions. Germany’s friends should wish it happy birthday — and pull their weight themselves.