KANDAHAR, Afghanistan — As the first chatter of gunfire began, a police unit tested its heavy machine gun.... And the government is desperate to defend Kandahar, a symbol of the state’s reach and an economic hub essential for trade to and from Pakistan through its checkpoints, bridges and highways.... He turns on an aging floor fan to try and dim the sounds of war long enough for them to get a few hours of sleep. The rusty appliance is a tepid defense to the hellaciously loud firefights that h