Meticulously planned by bin Laden and his al-Qaida terror network, Sept. 11 was just one of many salvoes in the "war against the infidels," but it was the one that changed the world forever.
"The pieces of the bodies of infidels were flying like dust particles. Had you seen it with your own eyes, you would have been very pleased, and your heart would have been filled with joy."
The above quote, taken from a self-penned poem recited by bin Laden at the wedding of one of his sons in January 2001, refers to the Oct. 12, 2000, suicide attack on the USS Cole in Yemen that killed 17 U.S. sailors.
The poem stands as a chilling preview of the slaughter bin Laden was preparing to unleash upon U.S. soil, and as a testament to the deep-seated roots of his beliefs.
Born in 1957 in the Saudi port of Jeddah, Osama was one of 57 children born to Yemeni construction magnate Mohammed Awad bin Laden.
The elder bin Laden was a devout Muslim with close ties to the Saudi royal family, who had amassed a great fortune through lucrative royal contracts.
Some who knew the young Osama described him as a quiet, pious youth, with a close relationship to his mother that he maintained into adulthood.
He was barely an adolescent when his father was killed in a helicopter crash. The craft was supposedly flown by a U.S. pilot.
Osama bin Laden's militancy began in earnest in 1979 following the Soviet invasion of Afghanistan. He went to Pakistan and met with resistance leaders, supporting the mujahedeen by organizing funds and shipments of weapons.
He would eventually take up arms and join the mujahedeen in their struggle to repel the invaders.
Men who fought alongside him recall a brave guerrilla fighter, unafraid of close combat and already a hardened opponent of the United States and its foreign policy.
However, true to the old saying "the enemy of my enemy is my friend," bin Laden at the time did not spurn support from U.S. intelligence services in the fight against the Russians, something which he later denied repeatedly.
Following the Soviet withdrawal from Afghanistan in 1989, bin Laden returned to Saudi Arabia, where he worked on expanding the family empire.
He maintained close links with Arab veterans of the Afghan conflict, establishing a contact network which would eventually form the foundations of terror group al-Qaida, Arabic for "The Base."
The fallout from the Iraqi invasion of Kuwait in 1991 provided the second turning point in bin Laden's life. He was shocked and dismayed when the House of Saud opted to allow the U.S. military to establish bases on Saudi soil.
Bin Laden regarded the presence of half a million U.S. troops in Saudi Arabia as a desecration of the holy Islamic sites of Mecca and Medina. He began writing treatises decrying the Saudi regime and lobbying religious figures for support in his campaign. Soon his close ties with the Saud rulers lay in tatters.
In 1991, bin Laden was expelled from the kingdom for his anti-regime activities. He took refuge in Sudan, where he spent the next five years assisting the Islamic administration with construction projects and rebuilding his financial empire.
In 1996, under pressure from the United States, bin Laden was expelled from Sudan and returned to Afghanistan. He began to forge strong ties with the ruling Taliban, whose radical Islamic faith bore a strong resemblance to the more puritanical Saudi elements that bin Laden identified with.
In Afghanistan, bin Laden surrounded himself with a private army and used his own resources to establish and fund a haven for potential terrorists. He declared a holy war against the U.S.
Veterans of the Afghan war and radical militant Muslims from all over the world found their way to bin Laden's camps, many willing to offer themselves as martyrs in suicide attacks.
"Infidels" is how bin Laden and his followers termed all those whom they held responsible for the repression of Muslims worldwide. The United States, Britain and Israel headed the list.
An audiotape released by Arabic television network al-Jazeera in February 2003 and purporting to be from bin Laden denounced some Arab leaders and warned of the consequences of assisting the so-called enemy. It urged Muslims worldwide to take up arms against the U.S.-led invasion of Iraq.
In his former homeland of Saudi Arabia, bin Laden enjoyed a resurgence in popularity among a strong anti-Western minority. That changed somewhat when more than 50 people, many of them Arabs, were killed in May 2003 in a series of terror attacks on foreign residential compounds in Riyadh.
For a small portion of Muslims worldwide, the Sept. 11 atrocities elevated bin Laden to the status he had always sought that of an avenging warrior unleashing fear and death upon those he labeled "infidels."