John's research focused on Vietnamese political and cultural evolution from the eleventh through the sixteenth centuries. When he began his work, during the height of the Vietnam War, antiwar activists had popularized an image of Vietnam as an ancient, homogeneous, historically stable "nation" whose struggle against the Americans simply continued an age-old struggle for independence from China. But, without getting involved in contemporary politics, John undertook fine-grained studies of Chinese-language Vietnamese sources to chart carefully the origin and evolution of Vietnamese identity. He discovered, first, that in the early centuries of the second millennium what is now northern Vietnam was home to three principal groups -- recent Chinese immigrants, older populations of mixed Chinese-indigenous origin, and upland communities speaking local Vietnamese dialects. In competitive and cooperative configurations these groups evolved and interacted, but there was no coherent Vietnamese identity on an elite level until the late fifteenth century, and on a popular level until very much later. To speak of a premodern "nation" is anachronistic. John was particularly interested in the long-term impact on Vietnamese society of Chinese and regional commercial currents. In his last years, he also charted the history in what is now central Vietnam of the Cham kingdom, for which he worked out an entirely new chronology and theoretical framework.
John was a scholar's scholar. A meticulous no-nonsense researcher, his conclusions followed wherever his primary materials led him. He was not the least reluctant to revise his own earlier interpretations in the light of new evidence; indeed he exulted in the joy of discovery. His love of research, his mastery of complex detail, his openness to new historiographic approaches, but also his uncompromising intellectual independence and disregard for fleeting fashion, were never far from the surface.
As a teacher, he was unfailingly patient, amiable, sympathetic, and encouraging. Students, although in awe of his expertise, eagerly sought him out. As a colleague, he was no less supportive. Most of what I know about early Vietnamese history I learned from John, both from his writings and from innumerable dinner conversations over many years.
We first met some 57 years ago when he was an instructor in an undergraduate course in Southeast Asian history that I took at Yale. Although our physical paths diverged not long thereafter, we remained in contact, only to find ourselves once again on the same campus, this time in Ann Arbor, in 1984. Since then we have remained in regular contact. For years we co-taught a U of M seminar on early Southeast Asia. And we saw one another on frequent social occasions. John was an unfailingly loyal and generous friend, and his passing will leave a hole in many people's lives.
John is survived by his former wife, three sons, and six grandchildren.