The bespectacled Egyptian doctor was al-Qaeda leader for the second half of that period. But he is perhaps best known for his previous role as Number 2 to Osama Bin Laden, the charismatic founder of one of the world’s most notorious and brutal terrorist organizations. It was only after bin Laden was killed in a US special forces raid in Pakistan in 2011 that Zawahiri took charge of the team, although he lacked the same ability of his close friend and ally to inspire his followers. Al Qaeda, under his rule, has struggled to make much of an impact, especially as its surviving leaders have been on the run or in hiding from US, British and other Western counterterrorism forces, while rival Islamist extremist groups have emerged, notably the Islamic State or ISIS , with a more savvy approach to social media and attracting more recruits. But Zawahiri, 71, remained – until the weekend – the most notorious Islamist militant to escape death or capture since US President George W. Bush launched the so-called “war on terror” following the massacre of Al Caida in Washington and New York. It means his death in a CIA drone strike in Kabul will be seen as a hugely significant moment for the thousands of American and British spies and special forces personnel who have never stopped hunting him as part of their mission to disrupt and to degrade al-Qaeda and stop the group from ever again posing an international threat. “They never forget,” US President Joe Biden said in an address to the nation on Monday night, confirming the news that Zawahiri was dead. He also revealed that the terror chief had moved to “central Kabul” to be reunited with his family. Pictured: Ayman al-Zawahiri, right, with Osama bin Laden in the picture that appeared in November 2001 “Comfortable upbringing” Such a risky move stands in stark contrast to the years Zawahiri has spent going to great lengths to hide his location – something he is widely believed to have succeeded in in Pakistan’s remote, tribal region bordering Afghanistan. It could even suggest that a highly controversial decision by the United States to withdraw its forces from Afghanistan in the face of a resurgent Taliban a year ago inadvertently created the conditions to lure Zawahiri out of the shadows. The Taliban have long maintained close ties to al-Qaeda despite promising to sever ties as part of the US withdrawal agreement. His death in a covert drone attack in Afghanistan is a far cry from Zawahiri’s comfortable start. He was born into a middle-class family in the Maadi suburb of Cairo on June 19, 1951. Zawahiri’s father was a professor of pharmacology. An academically gifted student, the young Zawahiri chose to study medicine at Cairo University. But he was also politically active, with increasingly extreme views against the Egyptian government. He founded the Jihad Group with several followers. A family man as well, Zawahiri married a woman named Azza Nowair and the couple had six children – one son and five daughters. Meeting with Osama Bin Laden He opened a medical practice, but became involved in visiting refugee camps along the Afghanistan-Pakistan border, according to a profile on Zawahiri by the Washington Post. Zawahiri used his medical training to treat the wounds of Afghan mujahideen fighters opposing the then Soviet-backed Afghan government. It was during this period that he reportedly first met Saudi Osama bin Laden. The unrest in Egypt following the assassination of the then Egyptian president in 1981 led to Zawahiri’s arrest and detention for three years. During this time he said he was tortured. After his release, he met bin Laden again and effectively became his personal physician as well as an increasingly trusted ally. An FBI wanted poster offering a reward of up to $25m (£20.4m) for information on his whereabouts said Zawahiri used various aliases, including The Doctor and The Teacher. Zawahiri, described as a thinker rather than a fighter, is believed to have spent much of the 1990s traveling the world, including the United States, Bulgaria, Denmark and Sweden, using fake passports, looking for new sources of funding. By 1997, he had settled in the city of Jalalabad, in southern Afghanistan. The next year his militant group merged with bin Laden’s more successful Al Qaeda – which is Arabic for “base”. Zawahiri is credited with helping to oversee the planning of the 9/11 attacks as well as other Al Qaeda atrocities. It also said it launched a failed attempt by the group to acquire biological and nuclear weapons before it was forced to flee the US-led invasion of Afghanistan. As bin Laden’s deputy, even while in hiding, Zawahiri appeared in numerous videos uploaded to al-Qaeda-sympathetic websites, promoting his terrorist views. After his boss’s death, however, and with friction within al-Qaeda’s ranks as well as among other Islamist extremist groups, Zawahiri adopted a lower profile, making far fewer appearances. But it remained as high a target as ever for US counterterrorism forces.