India's 1,300-mile Himalayan frontier with China is one of the world's most unlikely battlegrounds. Monsoon rains flood its approaches in summer, and snows blanket its jagged peaks and passes in winter. All year round, the thin air gnaws at the lungs and vitality of human trespassers in the fastness. Across the forbidding landscape, some 125,000 to 150,000 Chinese troops and more than 300,000 Indian jawans (infantrymen) are positioned in edgy, continuous confrontation.
Since the Chinese invaded India through the passes in 1962, the border has been comparatively quiet. The most recent major...