The announcement that Dr Ayman al-Zawahiri has assumed control of Al-Qaeda is not expected to galvanise a terrorist movement already weakened by years of attrition by US forces and the death of Osama bin Laden last month. Zawahiri was always the 'brains behind the Al-Qaeda operation, but hes never held the charismatic appeal of bin Laden and it seems unlikely he will attract the devotion of violent fighters. Bin Laden was fully aware of his appeal and used it to his advantage in addressing supporters. Nor is he a dominating figure, he lacks the looks, the height, and the presence of bin Laden. Zawahir was born in Egypt in 1953. He is the son of a wealthy and religiously conservative family. He was a quiet student but appear to have started down the road to radicalism after the Israelis devastating defeat of several Arab armies in 1967. Aged 14, he joined the Muslim Brotherhood and went on to become a member of Islamic Jihad. At the same time he was studying medicine and eventually qualified as a surgeon, but increasingly his time was taken up by radicalism. By the time of the assassination of President Sadat in 1981 he was a senior leader in Islamic Jihad. He was rounded up in the resulting crackdown, jailed for three years, and severely tortured whilst in prison. Upon release he struggled to find work in medicine due to his connections with Islamic Jihad and fled to Afghanistan to join the thousands of Arab fighters who had gone to fight the Soviets. There he met bin Laden and eventually the two men merged their different Mudjahiden groups to form 'The World Islamic Front for Jihad Against Jews And Crusaders, which became known as Al-Qaeda (AQ), and issued a declaration of war. Now that Zawahiri leads AQ he will want to make his mark -this will entail attempting a 'spectacular atrocity. But a security source told Sky News: Its not as if they havent been trying anyway and since the death of bin Laden, and the finding of so many documents, many senior members are simply trying to stay alive. Intelligence services around the world dont underestimate the continuing threat from AQ, but many experts point to the fact that at least a third of the higher echelons of the leadership has been killed of captured. This has led a change of structure inside the organisation and a presents a challenge for the new leader. AQ used to be hierarchical, with affiliated groups coming to central command for funding and approval for terrorist plots. Since the Americans went after them in 2001 the structure has changed. There are now many more 'franchise AQ groups. These have their own structures and their own leadership and without bin Laden they are far less likely to listen to orders or even advice from AQ Central. Al-Qaeda had already been severely weakened, Zawahiris assumption of leadership is unlikely to strengthen it. Sky News