On the evening of September 11, 2001, hours after two hijacked airliners had destroyed the World Trade Center towers and a third had hit the Pentagon building, President George W. Bush announced that the country was embarking on a new kind of war.

“America and our friends and allies join with all those who want peace and security in the world, and we stand together to win the war against terrorism,” Bush announced in a televised address to the nation.

It was Bush’s first use of the term that would come to define his presidency and deeply shape those of his three successors. The global war on terror, as the effort came to be known, was one of the most expansive and far-reaching policy initiatives in modern American history, and certainly the biggest of the 2000s.

It saw the US invade and depose the governments of two nations and engage in years- or decades-long occupations of each; the initiation of a new form of warfare via drones spanning thousands of miles of territory from Pakistan to Somalia to […]