I was thinking of the brilliant young Kennan who during the late 1920s and 1930s gazed out on the crumbling European order from Berlin and Prague and read the signs of the coming world conflict.

In Falluja I met his reincarnation in the person of a junior State Department official. This bright, aggressive young man spent his 20-hour days rumbling down the ruined streets with reluctant marine escorts, meeting Iraqis and writing tart cables back to Baghdad or Washington telling his bosses the truth of what was happening on the ground.

As I watched him joking and arguing with the local sheikhs, politicos and technocrats I thought of the indomitable young Kennan of the inter-war years, and of how, if the American effort in Iraq could ever be made to “work”, only undaunted and farseeing young men like this one, Kennan’s spiritual successor, could make it happen.

This was October 2005, on the eve of the nationwide referendum on Iraq’s proposed constitution. I had come to Falluja, the heart of rebellious Anbar province, to see whether the Sunnis could gather the political strength to vote it down.

The Sunnis had boycotted the first postSaddam election. This time, after Herculean efforts of persuasion by the American ambassador, most Sunnis were expected to vote. Would they affirm the political process or doom it?

After midnight, in the dimly lit American bunker on the eve of the vote, the young diplomat suddenly leant forward and confided quietly: “You know, tomorrow you are going to be surprised. Everybody is going to be surprised.

People here are not only going to vote. People here — a great many people here — are going to vote yes.”

I was stunned, but I took his words as an invaluable bit of inside wisdom from the American who knew this ground better than any other.

As I travelled from polling place to polling place a few hours later, however, Fallujans told me of their hatred for the constitution, which they believed was meant to divide and destroy Iraq. In fact, 97% of those who voted in the province voted no.

With all his contacts and commitment, with all his energy and brilliance, on the most basic and critical issue of politics on the ground my young “Kennan” had been entirely, catastrophically wrong.

The real Kennan, listening at 98 to the war drums in the autumn of 2002, had warned: “Today, if we went into Iraq, like the president would like us to do, you know where you begin. You never know where you are going to end.”

He knew from eight decades of experience to focus first of all on the problem of what you know and what you don’t know.