9/11

A terrorist attack on 11 September 2001 that killed a large number of people became known as 9/11. (PROSE: I Was a Monster!!!, The Danger Men)

The Laughing Gnome sent William Bishop's soul from 2011 into Calum Bence's body in 1999. Bishop had to overcome the urge to warn the authorities about 9/11, which was two years in the future. There were budget cuts to secret service espionage in 1999, but Bishop knew that changed after 9/11. (PROSE: The Danger Men)

In 2002, the Capricorn Killer wrote in his diary: "I want - no, I need - to be 9/11 not Big Brother."

In a 2003 book of essays, a historian wrote: "Following the attacks of September 11th 2001, we all know the problems of the world aren’t so easily defined, let alone solved." (PROSE: The Gallifrey Chronicles)

Mark Whitaker was a man from 2011 sent back in time to 1994 by the Weeping Angels. In 2003, he said to the Eleventh Doctor: (PROSE: Touched by an Angel)

"All the good people who have died, where I've stood by and done nothing. How do you think I felt on September the 11th, watching all those people die? But I did nothing."

- Mark Whitaker

After a false flag terrorist attack in 2005, (PROSE: Rise of the Dominator) an interviewer asked the Prime Minister if this event was "Britain's September 11th". Emily Chaudhry and Francis Currie remembered the 11 September attacks. The media wondered if the new attacks were due to British military action in Iraq and Syria. (AUDIO: The Longest Night)

Behind the scenes
The 9/11 terrorist attack was carried out by al-Qaeda; the World Trade Center was destroyed and the Pentagon was damaged. The War in Afghanistan and Iraq War followed 9/11, although these facts are not explicitly mentioned in DWU sources.