Abu Musab Al-Zarqawi was the foremost figure in a new breed of Islamic militant who took terror to new levels of brutality and in a few short years managed to eclipse Osama bin Laden and other al-Qaeda leaders.

Ruthless and vain but highly efficient, he was responsible for killing thousands of people, including hundreds of Shia Muslims. He quickly established himself as the main force in the Iraqi resistance against American occupation, intent on provoking Iraq's sectarian civil war.

Through his mastery of the internet, he spread his word globally in a way in which no other terrorist has succeeded. Where Osama Bin Laden relied on the Al Jazeera television network to broadcast his videos, Zarqawi circumvented this and published his messages and videos direct to his followers around the world.

He understood and harnessed the power of the internet. He recruited hundreds of suicide bombers, had brilliant intelligence and absolutely first-class bomb makers. He ran his operation on an industrial scale.

However, in recent months he became too extreme even for his allies. The success of his destructive campaign provoked concern and envy and turned all but the most hardline zealots against him.

Iraqis suffered most from his relentless assault, which included assassinations, beheadings and suicide bombings delivered on the streets of Baghdad.

The al-Qaeda leadership also become alarmed by the impact that his brutal methods was having on support in the Muslim World. Ayman al-Zawahiri, the al-Qaeda number two, wrote to al-Zarqawi last year urging him to stop the practice of beheading victims and posting the footage on the internet.

Arguably the most disastrous operation happened last November when three suicide bombers acting on al-Zarqawi’s orders killed 60 people in hotels in Amman. The victims included Palestinians attending a wedding celebration.

Most of the militias in Iraq are fighting for political ends, they have an agenda and their aim is to secure some kind of deal giving them power in Baghdad. Zarqawi wanted to provoke sectarian war and to establish a Sunni caliphate, which would have meant rejecting 80 per cent of Iraq's population as collaborators and heretics.

It was an impossible aim but he didn't care, seeing Iraq as a step on the way to achieving this ambition.

Fellow Sunni Muslims became increasingly alarmed by his nihilist ideology and the two sides clashed openly last year when Sunnis decided to participate in the general election against al-Zarqawi’s wishes.

In April this year al-Zarqawi was forced to accept a subordinate position inside a resistance umbrella group headed by Iraqis. A few days, in what appeared to be a bid to prove his relevance, he released a long video of himself clumsily firing a machine gun in the desert and plotting operations with is followers.

There is no question that Al Qaeda has lost on important figure today: there are plenty of bombmakers and insurgents with combat experience, but Zarqawi was an efficient organiser, good at PR, and good at gathering intelligence.

American, Iraqi and British leaders all welcomed today’s news that the terrorist mastermind had been killed. Some of his alleged supporters may also have breathed a sigh of relief.

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