On September 11 , 2001 , 53 Army civilians ( 47 employees and six contractors ) and 22 soldiers were among the 125 victims killed in the Pentagon in a terrorist attack when American Airlines Flight 77 commandeered by five Al-Qaeda hijackers slammed into the western side of the building , as part of the September 11 attacks . Lieutenant General Timothy Maude was the highest-ranking military official killed at the Pentagon , and the most senior U.S. Army officer killed by foreign action since the death of Lieutenant General Simon Bolivar Buckner , Jr. on June 18 , 1945 , in the Battle of Okinawa during World War II
American Airlines Flight 77
American Airlines Flight 77
History of the United States Army