On the morning of September 11, 2001, four commercial airline flights were hijacked by members of al-Qaeda, a terrorist group based in the Middle East. The first plane purposely crashed into the North Tower of the World Trade Center complex in Lower Manhattan. A second plane hit the South Tower moments later. Just over half an hour later, a third plane crashed into the west side of the Pentagon in Washington, D.C. The fourth went down in a field in Pennsylvania after a group of passengers overwhelmed the hijackers. It is suspected the fourth plane had originally targeted a building in Washington, D.C., possibly the Capitol or the White House. The attacks resulted in 2,977 deaths, countless injuries, and lingering health complications among survivors, first responders, volunteers, and local residents. September 11, 2001 is the deadliest terrorist attack in modern history.

In the aftermath of September 11, 2001, President George W. Bush’s administration recognized Osama bin Laden, leader of al-Qaeda, as the architect of that day’s events. A so-called “War on Terror” was announced with the goal of bringing Osama bin Laden and al-Qaeda to justice and preventing the development of other terrorist organizations. In October of 2001, the War in Afghanistan began after the Taliban, or Islamic Emirate of Afghanistan, refused to hand over Osama bin Laden.