THREE of my parishioners were killed in the Twin Towers last year.

They worked for Merrill Lynch, the huge commercial bank which has its European HQ right opposite my rectory. I have been close to Merrill Lynch ever since I came here from Yorkshire four years ago. Sometimes the closeness was uncomfortable, as at the start when the building wasn't completed: the first six months they were pile-driving, then steel-erecting, and then the concrete mixers were outside my front door day and night. Still, the church and the bank remained friends and my wife and I were guests at the official opening of the HQ by Prince Charles.

Last September, I was in Oxford when the news of the attacks on the US was broadcast. I came straight back to London and arranged a Requiem Mass for the day after. Even given so little notice, 250 people turned up for that lunchtime service. We did the first part in Latin: "Requiem aeternam dona eis, Domine; et lux perpetuam luceat eis". And the second part from the Book of Common Prayer. Only words of that depth and sonority could do justice to such a terrible occasion.

A month later we held a memorial service for the three people who had perished. Again the church was full. There were poems and readings, well-known hymns and, the highlight, a soaring soprano from our choir leading the singing of The Star-Spangled Banner. One year on and I shall say the Requiem again tomorrow lunchtime.

I notice that the newspapers and television are in the habit of referring to September 11, 2001 as "the day that changed everything". This is inaccurate. There were other atrocities leading up to September 11 which was, in fact, just a more severe attack on western civilisation than several others which had proceeded it. In the 1980s there was the killing by Islamic terrorists of 300 American servicemen in Lebanon. In the 1990s there were the attacks on a US warship and on two embassies in East Africa. Of course, those last two attacks occurred when Bill Clinton was in the White House and he had, as is well-known, rather more on his mind than dealing with murderous fanatics. So he fired a couple of cruise missiles into the desert and tried to behave as if the shocking incidents had never happened.

Thank God George W Bush was in the White House on September 11 last year. If that terrible day really was a day that changed everything, then the change was that it was the day when America began to fight back. As Mark Steyn wrote last week: "The passengers on the fourth hijacked aircraft understood they were on a flying bomb intended to kill thousands of their fellow-citizens. Todd Beamer on that plane got through to a telephone operator who told him about the planes that had smashed into the World Trade Centre. Mr Beamer asked her to pray with him, 'Yea though I walk through the valley of the shadow of death, I will fear no evil..." Then he and the others rushed the hijackers'." Thanks be to God.

* Peter Mullen is Rector of St Michael's, Cornhill, in the City of London, and Chaplain to the Stock Exchange