National Geographic : 1937 Oct
PEACETIME PLANT HUNTING ABOUT PEIPING 525 r.. Photograph by Gilbert Grosvenor A GLORIOUS PROMENADE, BUT INEFFECTUAL DEFENSE, IS MAN'S MIGHTIEST RAMPART Never in its more than 20 centuries has the 2,000-mile Great Wall withstood a major invasion. Genghis Khan's hordes and other fierce tribesmen poured down from the north onto the fertile plains surrounding Peiping. Japanese troops of 1937 reversed the direction, marching with tanks, planes, and heavy artillery northward from Peiping to dislodge Chinese defenders here at strategic Nankow Pass, where the highway and railroad to Kalgan pierce the massive barrier. Visitors who set out for a stroll along the wall soon start to puff as they climb the many steps, for this engineering marvel shoots uphill and down dale without regard to the steepness of the slopes.