Bamiyan, Afghanistan — The Soviets wouldn’t come up here with less than a battalion,” says Tim Lynch, a retired Marine Corps officer driving us down the two-lane blacktop that crosses the Shomali Plain, one of the largest and most fertile agricultural regions in Afghanistan. Alexander the Great founded the ancient city of Bagram on this plain, which opens up just north of Kabul, widens through Parwan Province, and finally dead-ends at the Salang and Panjshir rivers. Centuries later, Afghanistan’s Communist government would choose the same locale for a major air base, which today hosts the U.S.-led Coalition’s logistics-and-transshipment hub, Bagram …