Gen. David Petraeus told an audience of 1,700 that civilian and military leaders must “achieve unity of effort” after he arrived at the American embassy in Kabul to take over the fight in Afghanistan. Working together is “not optional” the general said, in the wake of Gen. Stanley McChrystal’s firing after he mocked civilian leaders in Rolling Stone. Petraeus added that the fight could get worse before it gets better; he’ll oversee an intensifying of the fighting in the Taliban stronghold of Kandahar after offensives in the area have already led to the worst month ever for coalition casualties in this war—102 soldiers died in June. American Ambassador to Afghanistan Karl Eikenberry, one of the men insulted in the McChrystal article, welcomed Petraeus and pledged commitment to the counterinsurgency strategy. Petraeus will meet Afghan President Hamid Karzai—a very vocal defender of McChrystal—Saturday.