September 11 and the War on Terror
Four hijacked planes, nearly 3,000 dead, and two decades of war
Quick facts
- Date
- September 11, 2001
- Deaths
- Nearly 3,000
- Targets
- World Trade Center, Pentagon, and Flight 93
- Response
- Wars in Afghanistan (2001) and Iraq (2003)
What happened
On the morning of September 11, 2001, four commercial airliners were hijacked. Two were flown into the twin towers of the World Trade Center in New York, which collapsed; a third struck the Pentagon outside Washington; and the fourth, United Flight 93, crashed in a field near Shanksville, Pennsylvania, after passengers fought back to stop it reaching Washington. Nearly 3,000 people were killed, the deadliest attack on American soil in the nation's history. The al-Qaeda network led by Osama bin Laden was responsible. In response the United States launched what it called the War on Terror, invading Afghanistan in October 2001 to remove the Taliban government that had sheltered al-Qaeda, and invading Iraq in 2003. The wars that followed lasted about two decades.
Why it matters
September 11 reshaped American life, foreign policy, and law: it led to two long wars, a vast expansion of surveillance and security powers, and a lasting sense of vulnerability. Debates over the wars, over torture and detention, over the balance between security and liberty, and over the costs and results of two decades of conflict have defined much of American politics in the twenty-first century.
How we know
The attacks are documented in an enormous record, including the official 9/11 Commission Report, and the timeline and casualties are preserved by the National Park Service at the Flight 93 National Memorial.
Sources
- National Park Service, Flight 93 National Memorial. September 11, 2001 Timeline · Primary source (author-declared)nps.gov · Cited as a "primary" source (no stronger domain match). · Link is live and its text matches the event's key terms (Jul 2026)
- National Park Service. Flight 93 National Memorial · Reputable sourcenps.gov · The domain "nps.gov" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
- HISTORY. September 11 Attacks · Reputable sourcehistory.com · The domain "history.com" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
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