John Ralph Willis was born in 1938 in Lorain, Ohio. He received his B.A. in history from the University of Arizona in 1960, and his M.A. from Boston University the following year. In the course of his graduate work, he was a Woodrow Wilson Fellow, a John Hay Whitney Opportunity Fellow, and a Mar- shall Scholar. In 1962–63 he was an administrative officer in the Peace Corps, concerned with a number of African countries, particularly Ghana and Sierra Leone. He continued his studies in African history at the School of Oriental and African Studies in London, where in 1970 he completed his Ph.D. dissertation under the title ‘Umar ibn Sa‘id al-Futi al-Turi (c. 1794–1864) and the Doctrinal Basis of His Islamist Reform Movement in the Western Sudan. By this time he had also embarked on an academic career and had taught at the University of Birmingham in England and the University of Wisconsin–Madison. In 1969 he was appointed assistant professor in the Department of History at the University of California–Berkeley. He came to Princeton in 1972 as associate professor of Near Eastern Studies. He has served as full professor in that department since 1984.

The major part of John’s scholarly work has centered on Islam in Africa; in particular, on the diffusion of Islam and Islamic institutions in West and North Africa.  His book, In the Path of Allah: The Passion of al-Hajj ‘Umar—An Essay into the Nature of Charisma in Islam, published in London in 1988, deals with an important figure in 19th-century African history: a man who was Muslim reformer, sufi, and warrior, and led a jihad, as he saw it, to purify and propagate Islam in West Africa, establishing a Muslim empire in the Western Sudan. John has also edited, and contributed to, books on African history, such as Studies in West African Islamic History: The Cultivators of Islam (1979) and Slaves and Slavery in Muslim Africa (1985). John’s articles and book chapters have dealt with a great variety of subjects These range from the Arabic writings of al-Hajj Umar—for which his research into the original sources took him to many archives and libraries, from the Bibliothèque National to the library of Seydu Nuru Tal in Dakar—to jihad and the ideology of enslavement, to legal responsa (fatwas) in Islam. To this last subject, on which he organized a highly successful conference at Princeton, he has devoted most of his recent research. Passing beyond the broad confines of his special field he also contributed to the biography of Ignatius Sancho, the 18th-century African-British letter-writer, poet, and musician; and, at the Princeton University Art Museum, he organized and wrote the catalogue for the bicentennial year exhibit of paintings by seven major African American painters of the 20th century.