General David Petraeus, the most celebrated military leader of his generation, stepped down as US commander in Afghanistan yesterday after a checkered year at the helm of what is America’s longest war.

At a ceremony in Kabul Gen. Petraeus passed the baton to John Allen, a former subordinate who made his name in Iraq by striking tribal alliances considered integral in reversing Al-Qaeda’s momentum after years of appalling violence.

Gen. Allen, who was promoted to a four-star general before the handover, becomes the first Marine to serve as head of the US-led war effort in Afghanistan.

Gen. Petraeus oversaw a surge of tens of thousands of troops into Afghanistan in a last-ditch bid to reverse a nearly 10-year Taliban insurgency and, although he has claimed some progress, violence remains at record highs.

He is leaving to head up the CIA, after a week in which Afghan President Hamid Karzai saw his younger brother and a key aide assassinated at their homes, and as Nato began transitioning areas of the country to Afghan control.

Washington has now started to draw down troop numbers under a controversial timetable, which Gen. Petraeus has admitted he did not recommend, that has attracted widespread criticism for being too fast to hold onto tentative gains.