What significant event occurred on September 11, 2001?

On September 11, 2001, a series of coordinated terrorist attacks were carried out by the extremist group al-Qaeda against the United States. This event is significant because it involved the hijacking of four commercial airliners, two of which were flown into the Twin Towers of the World Trade Center in New York City, causing the towers to collapse. A third plane struck the Pentagon, the headquarters of the U.S. Department of Defense, while the fourth, United Airlines Flight 93, was headed for a target in Washington, D.C. but crashed in Pennsylvania after passengers attempted to regain control from the hijackers.

The impact of these attacks was profound, leading to extensive loss of life, a reevaluation of national security policies, and significant military actions in the following years. This event also led to the establishment of the Department of Homeland Security and the implementation of various measures aimed at preventing future attacks, marking it as a pivotal moment in both U.S. and global history.