"We are pinned down. We are running low on ammo. We have no air. We've lost today," Marine Maj. Kevin Williams told his Afghan translator as Afghan soldiers repeatedly asked for helicopter support. American military trainers and the Afghan soldiers they were working with had been pinned down by intense machine gun, rocket-propelled grenade, and mortar fire for several hours, and the artillery support they had been promised was being withheld by commanders at a nearby forward operating base. The combined force of 60 Afghan National Army (ANA) soldiers, 20 Afghan border police, and 13 U.S. trainers set out before...