Although I opposed the Iraq war, I went on to serve in Iraq longer than any other British military or civilian official. When I testified before the Iraq inquiry on 14 January 2011, I explained how in 2003 I had responded to the government’s request for volunteers to administer Iraq for three months before we handed the country back to the Iraqis.

I felt I had useful skills to contribute, after a decade in Palestine working on capacity building and conflict mediation. And I did not want the only westerner Iraqis would meet to be a man with a gun.

Before I went out to Iraq I was not briefed, and had no idea what my job was going to be. I received a phone call from someone in the British government telling me to make my way to RAF Brize Norton, jump on a military plane and fly to Basra, where I would be met by someone carrying a sign with my name on it and taken to the nearest hotel.

It sounded plausible. It was June 2003. The invasion was three months previous. The war was apparently over. I assumed the British government knew what it was doing – it had just not told me. So I followed the instructions. But I arrived in Basra airport to find no one expecting me, no sign with my name.

The next day, I boarded a military plane to Baghdad, and found my way to the Republican Palace, which had been turned in to the headquarters of the CPA – the Coalition Provisional Authority. There I was given my first briefing.

I was told the situation in Iraq was stable; that there were enough staff in Baghdad; and that I should try the north. So after a week I found a flight to Mosul. They had someone there, so I travelled further. When I arrived in Kirkuk I was informed that I was the senior civilian there, in charge of the province, and reporting directly to the head of the CPA in Baghdad. I had never run a town in the UK – let alone a province in someone else’s country. I survived an assassination attempt in my first week on the job.

I went on to work as the political adviser to the top American generals from 2007-2010, through the surge and the drawdown of US troops.

The Iraq war led to the deaths of 179 British soldiers, 4,500 Americans and perhaps 200,000 Iraqis. It changed the regional balance of power in Iran’s favour, triggering proxy wars between Iran and Saudi Arabia, Turkey and the Gulf countries; and it created the chaotic conditions that enabled al-Qaida in Iraq, and then Islamic State, to gain traction. Millions of people have been displaced, many of them seeking refuge in Europe.

Britain should never have invaded Iraq in 2003 – the decision was based on the erroneous premise that Saddam Hussein had weapons of mass destruction; and, as my personal experience proved, the planning for the occupation was woefully inadequate. But the outcome of the intervention was not preordained or inevitable. There were different potential futures for Iraq.

Tomorrow Sir John Chilcot will finally make public his findings on the Iraq war. Released seven years after the inquiry was commissioned, and after considerable wrangling, it is unlikely to do much to restore public confidence in the integrity and judgment of elected officials – a key factor in the decision of the British electorate to leave the EU.

However, I hope the inquiry helps us better understand what happened in Iraq, so we learn not only the limitations of external actors in foreign lands, but also, importantly, where and how we can make a positive difference.

Sir John Chilcot, who led the Iraq war inquiry. Photograph: David Cheskin/PA

I hope it highlights to our political leaders and senior officials the importance of basing policy on realistic goals and assumptions; of developing a national strategy to bring about a political outcome; of using military force where necessary as a means not an end; of mediating between competing groups to broker an inclusive peace settlement; and of planning to avert state collapse.

I hope the report also acknowledges how, from 2007-9, the coalition helped restore stability by bringing all groups into the political process and by building up the capacity of the state. This was the only period when the coalition had the right strategy, the right leadership and the right resources. Things fell apart again after the 2010 parliamentary election results were contested – and the US rapidly disengaged, withdrawing all its forces.

The ghosts of the Iraq war have hung over Britain long enough, distorting the lens through which we view our leaders, our government, our allies and the Middle East. We need to put the Iraq war in perspective. It’s not about doing nothing. It’s about doing the right things.

Previous interventions saved thousands of lives in Iraqi Kurdistan in 1991, in Kosovo in 1999 and in Sierra Leone in 2000. We have done little in the face of mass murder in Syria and the displacement of half the Syrian people. Some may take satisfaction that we have kept our hands clean and not become mired in that country’s problems. But the failure of the international community to respond is a blot on our collective conscience. Furthermore, for years to come we will be plagued by the fallout from Syria of refugees, terrorism, militias and regional instability. In an interconnected world, the suffering of others affects us sooner or later.

We live in uncertain times and in a world in transition. But it is not possible in this day and age to isolate ourselves from these trends and transformations. In the months ahead, our new political leaders will have the opportunity to define Britain’s place in the world; to ensure government machinery that is effective and honest; and to help shape a vision for the new world order of the 21st century to replace the one we helped establish after the second world war, which is unravelling. Let us hope that these leaders will learn the right lessons from the Iraq war – and not for ever be blinded by it.

• Emma Sky will be a panel member for Chilcot: The Iraq War Inquiry, a Guardian Live event at King’s Place, London, on Thursday 7 July. For tickets go to the Guardian membership website