There were many untapped sources of materials in the Rockies and all of them were being exploited, but what was missing was food production. Prior to the first landing all holds had been released on agricultural production and the American agricultural juggernaut had responded magnificently. But most of the spare food had ended up being sent to the few fortified cities on the plains. They were scheduled to hold out for five years and food was their overriding concern. So there was, elsewhere, a severe shortage when the first massive landing occurred. Almost all the productive farmlands in the west, with the exception of the Klamath Basin, had been captured by the Posleen. So most of the food for the Western Sub-Urbs had to be provided over a long, thin link across the Northern Plains following I-94 and the Santa Fe Railroad. Sever that link and eighty-five million people would slowly starve to death.

In the east it was much the same. The Appalachian line stretched from New York to Georgia and linked up with the Tennessee River to create an uncrossable barrier from the St. Lawrence to the Mississippi. The Appalachians, however, were nothing compared to the Rockies. Not only were they lower throughout, but they had passes that were nearly as open as flatland. Thus the Posleen found numerous places to assault all along the line. And the fighting at all of them, Roanoke, Rochester, Chattanooga and others, had been intense and bloody. In all the gaps regular formations, mixed with Galactic Armored Combat Suits and the elite Ten Thousand, battled day and night against seemingly unending waves of Posleen. But the lines held. They held at times only because the survivors of an assault were too tired to run, but they held. They bent from time to time but nowhere had they ever been fully sundered.