The Battle of Tora Bora was a military engagement that took place in Afghanistan in December 2001, during the opening stages of the war in that country launched following the 9/11 attacks on the United States. The U.S. and its allies believed that al-Qaeda leader Osama bin Laden was hiding in the rugged mountains at Tora Bora, but despite overrunning the Taliban and al-Qaeda positions they failed to kill or capture him.