When the Twin Towers fell in 2001, Niall Ferguson wrote that the attack was a result of complex historical trends—post-2000 economic downturn, the rise of American imperialism, and the fragmentation of ethnic pluralism in Western nations. But Niall now thinks he was wrong. And he explains why in his essay for The Free Press today. Read it below, and then read Matt Labash’s dispatch from the streets of New York City after the attack, which we’re honored to republish today: “South Toward Hell After September 11.” —The Editors

This week’s azure September skies over New York brought back memories. Twenty-four years ago, I was due to give a lecture at New York University. The date of the lecture was 9/12. I never flew.

On the day of the attacks, I sat in my study at Jesus College, Oxford, staring incredulously at the pixelated live video of the Twin Towers first blazing, then collapsing. Not long after, in April 2002, I accepted a chair at the Stern School of Business at NYU and resigned my Oxford professorship.

My motivation was partly the hereditary Scottish tendency to march toward the sound of gunfire. As a teenager in 1914, my grandfather John Ferguson had volunteered to fight the Germans. This seemed easier.

Regardless of the 9/11 attackers’ motives, I had a strong objection to terrorism as a political method—a result of growing up in Glasgow in the 1970s, when “the Troubles” in nearby Northern Ireland did more than merely resonate. My first impulse after the attacks, in a piece for The New York Times, was to liken the sympathetic British reaction to 9/11 to the American reaction to the Blitz of 1940-41. But I also warned Americans to “steel themselves for a long, inglorious kind of war that governments in Europe already know only too well.” In wars against terrorists, I wrote, “there are no quick victories. The foe does not line up his tanks for you to flatten, his ships for you to sink. His troops live among you.”

Yet this was not the Provisional IRA. Rereading a transcript of Osama bin Laden’s first post-9/11 video, from November 3, 2001, I am reminded how explicitly he declared a war of religion. “People were divided into two parts” after 9/11, he declared. “The first part supported these strikes against U.S. tyranny, while the second denounced them.”

“The vast majority of the sons of the Islamic world were happy about these strikes,” bin Laden went on, “because they believe that the strikes were in reaction to the huge criminality practiced by Israel and the United States in Palestine and other Muslim countries.” There were demonstrations of support for his action “from the farthest point in the eastern part of the Islamic world to the farthest point in the western part of the Islamic world.” This revealed the key reality: “This war is fundamentally religious. The people of the East are Muslims. They sympathized with Muslims against the people of the West, who are the crusaders.”...