Timeline: How September 11, 2001 led to US’s longest war

How the 9/11 attacks led to the US’s 20-year deployment in Afghanistan and chaotic withdrawal.

The September 11, 2001 attacks on the United States set off a series of events that would see Washington – in just a month – begin the longest war in the country’s history. Twenty years later, the US will mark the anniversary of the attacks less than two weeks after completing a chaotic withdrawal from the now Taliban-controlled country. The 20-year conflict left about 69,000 Afghan security forces and at least 51,000 Afghan civilians dead, according to research by Brown University. About 2,500 members of the US military and 1,144 members of allied-NATO militaries died during the fighting.