As the convoy approached Mosul, an Iraqi man looked toward Tech. Sgt. Bob Busse and slid his hand across his throat. A short while later, the assemblage of about 70 gun trucks, armored Stryker vehicles, tractor trailers and heavy equipment transporters entered a section of Mosul that only a few days prior was the scene of a bustling outdoor market. On this day, however, “it was eerily quiet,” said Tech. Sgt. Robert Weis, who viewed the abandoned setting from the driver's seat of a 5-ton Air Force gun truck. “We looked at each other and said, ‘this is not good.'”...