U.S. soldier and author whose knowledge of Japanese affairs enabled him, 30 years before World War II, to predict a U.S.-Japanese war and describe its early course.

Lea studied law at Stanford University, Palo Alto, Calif. Intensely interested in military history and strategy and unable for medical reasons to join the U.S. Army, he went in 1899 to China, where he soon was in command of a body of volunteers for K'ang Yu-wei (Kang Youwei), who was a leading reformer during the last years of the Ch'ing dynasty. When the reformers (Hundred Days of Reform) were repudiated by the empress dowager, Tz'u Hsi, Lea and others who engaged in reform activities fled to Hong Kong. While there Lea met Sun Yat-sen. He went with Sun to Japan and later became his chief of staff.

In 1901 Lea returned to the United States. He was back in China in 1904 for a short time, then returned permanently to California, where he wrote a novel of the Manchu regime, The Vermilion Pencil (1908), and dictated his well-known military analysis, The Valor of Ignorance (1909). In the latter work, Lea predicted a U.S.-Japanese war in which Hawaii (Pearl Harbor attack) would be the key position and specified how the Japanese would conquer the Philippines and attempt an invasion of the United States proper along the coast of Washington and Oregon.