When China thought America might invade

When foreign foes threaten, an impregnable fortress is worth more than a comfortable home. Time and again, that doctrine guided China's Communist Party in its first decades of rule. Under Chairman Mao Zedong, talk of invasion was a constant. In those dark times, the usual priorities of peacetime government—feeding and clothing the masses, striving to raise living standards—were all too often neglected. In their stead came campaigns to ready China for war. One such campaign built a complete military-industrial complex in China's inland mountains, known as the "Third Front”. Begun in 1964, it was a state secret for more than…