The late John Nottingham once shared a story with me—possibly at his office on Kimathi Street, or at Art Caffé in Westlands, where we met in later years—about his posting as a district officer in Machakos. Tasked with tracking down those who were involved in witchcraft and had possibly administered the Mau Mau oath in the southern part of the largely Kamba district, Nottingham’s research had uncovered some unlikely suspects. Convinced, though, of the correctness of his investigations, Nottingham decided to carry out his duty. He entered a church in the middle of Sunday morning services, quietly walked down the aisle, and proceeded to arrest the occupants of the front two pews. Nottingham’s intervention reflected the complexities of the ways in which Mau Mau had an impact on Kenya’s communities. It was contradictory, divisive, and secretive, and it continues to exhibit those characteristics to the present day.

I open this review with Nottingham for a second reason: in 1966, it was he who—together with the Berkeley political scientist Carl Rosberg—published the seminal The Myth of “Mau Mau”: Nationalism in Kenya. Rosberg and Nottingham’s volume was one of the earliest efforts to depict Mau Mau as a rational and organized response to colonial maladministration and to reject the prevailing orthodoxy that it was an atavistic outbreak of violence. Their view of Mau Mau as a nationalist movement is the approach that defines Mickie Mwanzia Koster’s new book, The Power of the Oath: Mau Mau Nationalism in Kenya. Mwanzia Koster argues, “how and why different ethnic communities united during Mau Mau,” oddly without discussing Rosberg and Nottingham’s work or mentioning their historiographical contribution (154). For the author—in contrast to most contemporary understandings—Mau Mau drew Kenyans together in a joint struggle for freedom, though at times she appears to hedge on this assertion.

Mwanzia Koster unpacks her argument by focusing on the Mau Mau oath, a worthy topic for study that has remained one of the few gaps in a crowded marketplace. She pays particular attention to women’s experiences during the war and analyzes a wide variety of differing oathing texts and testimonies, though working more deeply in the Kikuyu or Kamba languages might have been even more revealing. Her attention to the experience of women in the oathing process is fascinating, and her efforts to unpack the symbolism of the oaths an important contribution. There is a tendency, however, to assert an argument as opposed to utilizing evidence to prove it. Of great interest, too, is her original effort to read the texts of legal trials involving Mau Mau detainees for content about the oathing process. Unfortunately, though, one is left unsatisfied: her argument here is built almost entirely around just three archival files. This six-chapter text culminates with an analysis of the “cleansing” of Mau Mau oaths.

In order to demonstrate how Mau Mau was a nationalist struggle, the author uses the Kamba—close cousins to the Kikuyu—to demonstrate its wider appeal. The Kamba, indeed, are the cornerstone of her argument, and to read this book, one would leave believing that the entire Kamba community sympathized with or was involved in the movement. This is false: the majority of the Kamba roundly rejected Mau Mau and had carefully considered and complex reasons for doing so. Indeed, I explored these topics in great depth—as well as the actual involvement of the Kamba in Mau Mau—in Ethnicity and Empire in Kenya: Loyalty and Martial Race among the Kamba, c. 1800 to the Present (Cambridge University Press 2014), one of several highly relevant texts that go unmentioned and uncited. Mwanzia Koster or her research assistants seem to have carried out interviews with only Mau Mau supporters or participants (largely from the known hotbeds of Mbitini and Kilungu, in part the result of the railway line’s presence), which skews her information. The voices of those who rejected the movement are absent, as are those of loyalist Kikuyu. As Daniel Branch has emphatically demonstrated, the category of “loyalist” was complex and flexible; for Mwanzia Koster, it neatly and clearly divided Kenyans. Indeed, much of the intricate and rich historiography on Mau Mau (one thinks immediately of John Lonsdale’s oeuvre, or Kate Luongo from the Kamba perspective) is cited in the Bibliography but the author rarely grapples with it the text itself.

Mwanzia Koster is right to treat colonial sources through a critical lens, and it is noteworthy that she channels the words of her interviewees. This does, however, produce one of the volume’s most significant weaknesses: she tends to assume oral testimony is factually incontrovertible, which ignores the important effects of time and political and social debate over the past sixty years of Mau Mau history. The overwhelming feeling, as a result, is unfortunately one of missed opportunity.