KHAKREZ DISTRICT, Afghanistan — Intensified fighting and a larger troop presence in Afghanistan in 2010 led to the highest American combat casualties yet in the war, as the number of troops wounded by bullets, shrapnel and bombs approached that of the bloodiest periods of the war in Iraq. Multimedia Slide Show Speeding the War Wounded to Care Tyler Hicks/The New York Times The number of medevac helicopters in service has risen sharply, meaning more of the war’s wounded are being saved. More Photos