LONDON (Reuters) - Challenging the might of the "infidel" United States, Osama bin Laden masterminded the deadliest militant attacks in history and then built a global network of allies to wage a "holy war" intended to outlive him.
The man behind the suicide hijack attacks of Sept. 11, 2001, and who U.S. officials said late on Sunday was dead, was the nemesis of former President George W. Bush, who pledged to take him "dead or alive" and whose two terms were dominated by a "war on terror" against his al Qaeda network.
Bin Laden also assailed Bush's successor, Barack Obama, dismissing a new beginning with Muslims he offered in a 2009 speech as sowing "seeds for hatred and revenge against America".
Widely assumed to be hiding in Pakistan -- whether in a mountain cave or a bustling city -- bin Laden was believed to be largely bereft of operational control, under threat from U.S. drone strikes and struggling with disenchantment among former supporters alienated by suicide attacks in Iraq in 2004-06.
But even as political and security pressures grew on him in 2009-2010, the Saudi-born militant appeared to hit upon a strategy of smaller, more easily-organised attacks, carried out by globally-scattered hubs of sympathisers and affiliate groups.
Al Qaeda sprouted new offshoots in Yemen, Iraq and North Africa and directed or inspired attacks from Bali to Britain to the United States, where a Nigerian Islamist made a botched attempt to down an airliner over Detroit on Dec 25, 2009.
While remaining the potent figurehead of al Qaeda, bin Laden turned its core leadership from an organisation that executed complex team-based attacks into a propaganda hub that cultivated affiliated groups to organise and strike on their own.
With his long grey beard and wistful expression, bin Laden became one of the most instantly recognisable people on the planet, his gaunt face staring out from propaganda videos and framed on a U.S. website offering a $25 million bounty.
Officials say U.S. authorities have recovered bin Laden's body, ending the largest manhunt in history involving thousands of U.S. troops in Afghanistan and tens of thousands of Pakistani soldiers in the rugged mountains along the border.
Whether reviled as a terrorist and mass murderer or hailed as the champion of oppressed Muslims fighting injustice and humiliation, bin Laden changed the course of history.
The United States and its allies rewrote their security doctrines, struggling to adjust from Cold War-style confrontation between states to a new brand of transnational "asymmetric warfare" against small cells of Islamist militants.
Al Qaeda's weapons were not tanks, submarines and aircraft carriers but the everyday tools of globalisation and 21st century technology -- among them the Internet, which it eagerly exploited for propaganda, training and recruitment.
But, by his own account, not even bin Laden anticipated the full impact of using 19 suicide hijackers to turn passenger aircraft into guided missiles and slam them into buildings that symbolised U.S. financial and military power.
Nearly 3,000 people died when two planes struck New York's World Trade Center, a third hit the Pentagon in Washington and a fourth crashed in a field in rural Pennsylvania after passengers rushed the hijackers.
"Here is America struck by God Almighty in one of its vital organs," bin Laden said in a statement a month after the Sept. 11 attacks, urging Muslims to rise up and join a global battle between "the camp of the faithful and the camp of the infidels".
In video and audio messages over the next seven years, the al Qaeda leader goaded Washington and its allies. His diatribes lurched across a range of topics, from the war in Iraq to U.S. politics, the subprime mortgage crisis and even climate change.
A gap of nearly three years in his output of video messages revived speculation he might be gravely ill with a kidney problem or even have died, but bin Laden was back on screen in September 2007, telling Americans their country was vulnerable despite its economic and military power.
Born in Saudi Arabia in 1957, one of more than 50 children of millionaire businessman Mohamed bin Laden, he lost his father while still a boy -- killed in a plane crash, apparently due to an error by his American pilot.
Osama's first marriage, to a Syrian cousin, came at the age of 17, and he is reported to have at least 23 children from at least five wives. Part of a family that made its fortune in the oil-funded Saudi construction boom, bin Laden was a shy boy and an average student, who took a degree in civil engineering.
He went to Pakistan soon after the 1979 Soviet invasion of Afghanistan, and raised funds at home before making his way to the Afghan front lines and developing militant training camps.
According to some accounts, he helped form al Qaeda ("The Base") in the dying days of the Soviet occupation. A book by U.S. writer Steve Coll, "The Bin Ladens", suggested the death in 1988 of his extrovert half-brother Salem -- again in a plane crash -- was an important factor in Osama's radicalisation.
Bin Laden condemned the presence in Saudi Arabia of U.S. troops sent to eject Iraqi forces from Kuwait after the 1990 invasion, and remained convinced that the Muslim world was the victim of international terrorism engineered by America.
He called for a jihad against the United States, which had spent billions of dollars bankrolling the Afghan resistance in which he had fought.
TRAIL OF ATTACKS
Al Qaeda embarked on a trail of attacks, beginning with the 1993 World Trade Center bombing that killed six and first raised the spectre of Islamist extremism spreading to the United States.
Bin Laden was the prime suspect in bombings of U.S. servicemen in Saudi Arabia in 1995 and 1996 as well as attacks on U.S. embassies in Kenya and Tanzania in 1998 that killed 224.
In October 2000, suicide bombers rammed into the USS Cole warship in Yemen, killing 17 sailors, and al Qaeda was blamed.
Disowned by his family and stripped of Saudi citizenship, bin Laden had moved first to Sudan in 1991 and later resurfaced in Afghanistan before the Taliban seized Kabul in 1996.
With his wealth, largesse and shared radical Muslim ideology, bin Laden soon eased his way into inner Taliban circles as they imposed their rigid interpretation of Islam.
From Afghanistan, bin Laden issued religious decrees against U.S. soldiers and ran training camps where militants were groomed for a global campaign of violence.
Recruits were drawn from Central, South and Southeast Asia, the Middle East, Africa and even Europe by their common hatred of the United States, Israel and moderate Muslim governments, as well as a desire for a more fundamentalist brand of Islam.
After the 1998 attacks on two of its African embassies, the United States fired dozens of cruise missiles at Afghanistan, targeting al Qaeda training camps. Bin Laden escaped unscathed.
The Taliban paid a heavy price for sheltering bin Laden and his fighters, suffering a humiliating defeat after a U.S.-led invasion in the weeks after the Sept. 11 attacks.
ESCAPE FROM TORA BORA
Al Qaeda was badly weakened, with many fighters killed or captured. Bin Laden vanished -- some reports say U.S. bombs narrowly missed him in late 2001 as he and his forces slipped out of Afghanistan's Tora Bora mountains and into Pakistan.
But the start of the Iraq war in 2003 produced a fresh surge of recruits for al Qaeda due to opposition to the U.S. invasion within Muslim communities around the world, analysts say.
Apparently protected by the Afghan Taliban in their northwest Pakistani strongholds, bin Laden also built ties to an array of south Asian militant groups and backed a bloody revolt by the Pakistani Taliban against the Islamabad government.
Amid a reinvigorated al Qaeda propaganda push, operatives or sympathisers were blamed for attacks from Indonesia and Pakistan to Iraq, Turkey, Egypt, Kenya, Morocco, Algeria, Mauritania, Tunisia, Saudi Arabia, Yemen, Spain, Britain and Somalia.
Tougher security in the West and killings of middle-rank Qaeda men helped weaken the group, and some followers noted critically that the last successful al Qaeda-linked strike in a Western country was the 2005 London bombings that killed 52.
But Western worries about radicalisation grew following a string of incidents involving U.S.-based radicals in 2009-10 including an attempt to bomb New York's Times Square.
In a 2006 audio message, bin Laden alluded to the U.S. hunt for him and stated his determination to avoid capture: "I swear not to die but a free man."
(Editing by William Maclean)