On 16 September 2001, at Camp David, President George W. Bush used the phrase war on terrorism in an unscripted and controversial comment when he said, "This crusade – this war on terrorism – is going to take a while, ... " Bush later apologized for this remark due to the negative connotations the term crusade has to people, e.g. of Muslim faith. The word crusade was not used again. On 20 September 2001, during a televised address to a joint session of congress, Bush stated that, "(o)ur 'war on terror' begins with al-Qaeda, but it does not end there. It will not end until every terrorist group of global reach has been found, stopped, and defeated."
The Federal Detention Center (FDC Philadelphia) is a United States Federal prison in Center City, Philadelphia, Pennsylvania which holds male and female inmates prior to or during court proceedings, as well as inmates serving brief sentences. It is operated by the Federal Bureau of Prisons, a division of the United States Department of Justice.
Margaret Mead, the first of five children, was born in Philadelphia, but raised in nearby Doylestown, Pennsylvania. Her father, Edward Sherwood Mead, was a professor of finance at the Wharton School of the University of Pennsylvania, and her mother, Emily (née Fogg) Mead, was a sociologist who studied Italian immigrants. Her sister Katharine (1906–1907) died at the age of nine months. This was a traumatic event for Mead, who had named the girl, and thoughts of her lost sister permeated her daydreams for many years. Her family moved frequently, so her early education was directed by her grandmother until, at age 11, she was enrolled by her family at Buckingham Friends School in Lahaska, Pennsylvania. Her family owned the Longland farm from 1912 to 1926. Born into a family of various religious outlooks, she searched for a form of religion that gave an expression of the faith that she had been formally acquainted with, Christianity. In doing so, she found the rituals of the Episcopal Church to fit the expression of religion she was seeking. Mead studied one year, 1919, at DePauw University, then transferred to Barnard College where she found anthropology mired in "the stupid underbrush of nineteenth century arguments."
Journalist Yosri Fouda of the Arabic television channel Al Jazeera reported that in April 2002 Khalid Sheikh Mohammed admitted his involvement in the attacks, along with Ramzi bin al-Shibh. The 9/11 Commission Report determined that the animosity towards the United States felt by Mohammed, the principal architect of the 9/11 attacks, stemmed from his "violent disagreement with U.S. foreign policy favoring Israel". Mohammed was also an adviser and financier of the 1993 World Trade Center bombing and the uncle of Ramzi Yousef, the lead bomber in that attack.Mohammed was arrested on March 1, 2003, in Rawalpindi, Pakistan, by Pakistani security officials working with the CIA. He was then held at multiple CIA secret prisons and Guantanamo Bay where he was interrogated and tortured with methods including waterboarding. During U.S. hearings at Guantanamo Bay in March 2007, Mohammed again confessed his responsibility for the attacks, stating he "was responsible for the 9/11 operation from A to Z" and that his statement was not made under duress.

Question: A nation which has a Federal Detention Center in the birthplace of Margaret Mead has been attacked by a terrorist group who Bush targeted with the 'war on terror'. What is the biggest attack by that group on that nation?
Answer: the 9/11 attacks