CAMP AL ASAD, Iraq -- Sucked beyond the western horizon the night before, sunlight seeps back into the valley here, in an everlasting give-and-take.Such as the insatiable west in celestial cycles, Marines' stomachs, gas tanks and weapons cry for more and more. From the east emerges the provider.With the growing light, Marines funnel from their barracks' beds to a narrow lot where their behemoth trucks, wearing coats of muted green and black or tan paint, were parked the night before in three neat rows.Both man and machine are rested, and the latter's engines are cool from a night of rest. Soon, though, they too will awaken, grumbling.For the Marines of Combat Service Support Battalion 7 here, their return to the road is perpetual, and in the moments before they climb behind steering wheels and heavy machine guns, they scurry over, under and through the columns of vehicles making final preparations. Odometer readings are scrawled down on vehicle logs; weapons are lubricated; cargo straps are cinched tighter.This battalion alone shoulders a heavy load -- delivering life-sustaining supplies to fellow Marines operating across Iraq's vast western province the size of Wyoming. Since March 2004, approximately 5 million pounds of cargo have rested on the beds of these trucks during scorching, dusty treks, some spanning hundreds of miles.By now, to most Marines, putting a convoy on the road is mere reflex. Still, they gather ritualistically to review the mission: where they're going, which route they'll take, who's in charge, what to do if insurgents say hello.Ever repeating shouts domino down the lines of steadily awakening trucks announcing the minutes remaining before the logistics train chugs away on its way. Marines don flak jackets, sandwiching themselves with armored plates. Helmets settle atop their close-cropped heads.And with the bottom of the sun separated from the horizon, the Marines' day officially begins.They have mouths to feed.