The phrase "what happened in 9" could refer to multiple things, but based on the search results, the most significant and widely known event associated with "9" in recent history is the September 11 attacks in 2001, often called 9/11. On September 11, 2001, a series of coordinated terrorist attacks were carried out by the Islamist extremist group al-Qaeda against the United States. Nineteen terrorists hijacked four commercial airplanes. Two planes were flown into the Twin Towers of the World Trade Center in New York City, causing both towers to collapse within two hours. A third plane was crashed into the Pentagon near Washington, D.C., and the fourth plane crashed in Pennsylvania after passengers attempted to retake control from the hijackers. Nearly 3,000 people died in these attacks, including civilians, emergency responders, and military personnel. The attacks had widespread global repercussions, leading to the U.S. War on Terror, invasions of Afghanistan and Iraq, and major changes in U.S. and global security policies.
If the user intended a different meaning for "9," additional context would be needed. But this explanation covers the most historically significant and recognized event related to "9" as the shorthand for September 11 attacks.
