So farewell then Kofi Annan. Later this week you'll make your last public pronouncement and then it will be time to start clearing your desk on the 38th floor of the UN building in New York, your embattled eyrie for the past 10 years. Difficult though it is to believe that your restless soul will accept carpet slippers and a seat at the fireside, ahead lies the anonymity of retirement and a chance to look back at your time in the world's hot seat.

It has been quite a ride. During Annan's watch, the world has witnessed crisis after crisis, and he did not have to go out of his way to look for trouble; it came looking for him. From the outset, the Balkans was the first real test of the UN's ability to deal with crisis management, in what should be called the wars of the Yugoslav succession, and initially it failed the test. Not since the second world war had the world seen displacement on such a huge scale as the new republic of Bosnia-Herzegovina learned the grim lesson that national recognition did not mean international protection.

Africa provided other equally stark reminders that the writ of the UN does not run as far or as strongly as the founders might have wished in 1945. Somalia imploded into violence and self-hatred; hunger and death marched into Darfur; civil war in Ethiopia told the world all it needed to know about the bloody anarchy of internecine combat. Then there was, and is, the long agony of the Middle East, exacerbated by the unwillingness of a US government to learn the lessons of history. And, of course, the September 2001 attacks on the US homeland changed the world forever and ushered in a new dark age in which calls for peacekeeping forces or the secretary-general's special missions seemed to be little more than fingers in a dyke.

In the midst of the mayhem, it did not help matters that the US was on a collision course with the UN and did all that it could to undermine Annan's position. This was personally painful to the secretary-general as he is American-educated and, like anyone who has witnessed the broad minds and enquiring nature of the liberal intelligentsia, he has a deep respect for the best values of US society. Let's not forget that Annan was Washington's choice back in 1996 and it was only later when the Bush administration came to power that he was transmogrified into "the enemy".

The falling-out was all down to Iraq during the 1990s, when Annan attempted to keep the peace by maintaining sanctions and running the now-discredited oil-for-food programme. It didn't help that Annan's son got his fingers dirty in the process, but from the outset Bush and his team were going to ride roughshod over the UN to get their way by invading Iraq in 2003.

Annan did his best to avert disaster but by the time the question of weapons of mass destruction was being debated in the Security Council it was clear that people who should have known better, such as secretary of state Colin Powell, weren't going to yield an inch.

Washington's high-handed treatment should have made Annan bitter but on the eve of his retirement this mild-mannered man is busy telling anyone who will listen that the UN must sponsor a regional conference along the lines suggested by the Iraq Study Group.

In the succession of UN secretary-generals, Annan was not a natural leader in a way that second holder of the post Dag Hammarskjold was, but he is that rare creature in the world of diplomacy - a thoroughly decent man.