Without intending blasphemy, his U.S. assistants called him "Todd Almighty." He was trying to change the geography of a valley where 50,000,000 lived; he was trying to lift a terror that had recurred decade after decade for more than eight centuries; he was trying to create a farm region as big as Iowa. Oliver J. Todd of Palo Alto, Calif., engineer and humanitarian, was fighting the Yellow River.
Through the golden-green wheatfields of Honan Province, the twelfth longest river in the world ran sluggishly thick with yellowish silt from the loess lands of China's northwest. On its soggy banks last...