Jonathan Gray introduces this important study of oaths and the Henrician Reformation by reminding us of the difficulties the London Charterhouse experienced in 1534–1535. A royal commission insisted that the Carthusians take the oath of succession, swearing their fidelity to the king, his new wife Anne, and their heirs, and swearing also that Henry's previous marriage to Katherine of Aragon was illegitimate. Later in the summer the Carthusians were confronted with a demand for a new oath acknowledging that Henry was the supreme head of the church in England under God, and that the Pope, the bishop of Rome, had no jurisdictional rights in England. Pleading that they could not break their previous oath to the Pope, the Carthusians initially resisted, but ultimately all but ten took the oath and the Charterhouse was dissolved. The ten resisters were famously trooped off to Newgate where they were starved to death.

That demonstration of royal determination to brook no opposition was followed by the execution of Queen Anne, of Sir Thomas More and Bishop John Fisher for refusing the oath, of various Pilgrims of Grace following the dissolution of the monasteries, and of a handful of conservative opponents and evangelical heretics, as the Reformation unfolded. Gray in no way denies the importance of events such as the authorization of the Bible in English, the dissolution of the monasteries, the enactment of the conservative Six Articles, and the fall of Thomas Cromwell, but he insists that oaths were only employed to sanction the Acts of Succession and Supremacy where the issue was acquiescence and obedience, loyalty and allegiance. Gray agrees with Richard Rex in seeing what unifies these disparate measures and events as the overriding need for obedience. “The crux of the Henrician Reformation was royal supremacy, and oaths were the primary means through which royal supremacy was implemented” (115).

The beauty of oaths was that they provided a sanction well beyond the limited policing powers of the Tudor state. In a substantial chapter Gray analyzes the nature and understanding of oaths and oath-taking in Catholic and Protestant theory and practice. In simplest terms a mere promise depends on the sincerity and intention of the person promising, whereas swearing an oath invokes God, who searches the heart and knows if one equivocates, has mental reservations, or swears falsely—in short, at least in theory God is guarantor of the truth of the oath and can visit divine wrath on the deceiver. It was this quality that made the sworn oath superior to mere subscription in securing the recognition of the Act of Succession and why Henry attempted (and largely succeeded) in imposing such an oath on every male in the realm. The clerical order in general, and the archbishops and bishops and the priors of the preaching orders in particular, posed a special problem, for they had all explicitly or in the course of ordination or induction sworn an oath to the papacy and to uphold the Catholic Church. Hence, Gray shows in great detail the complex process by which the regime sought to secure the allegiance of the king's male subjects and the variant oaths imposed in 1534 on the various parts of the clerical order, including Oxford and Cambridge colleges and even the parochial clergy, as well as on the House of Lords, the Commons in Parliament, the gentry, sheriffs, and others in the shires. (In a lengthy appendix Gray provides the texts of the oaths and professions made by the various subsets of English society in 1534 and 1535 and the new oath prescribed by the new Act of Succession of 1544). Gray does not disguise the chaos multiple royal commissions riding about the countryside must have created in the summer and early autumn of 1534.

The Pilgrimage of Grace in opposition to the new order, specifically the act suppressing the lesser monasteries, which broke out in Lincolnshire in October 1536, generated, as Gray shows, a veritable war of oaths. Attempting the impossible feat of preserving the sanctity of their previous oaths of succession, they swore each new recruit to the rebellion to be true to God, the king, and the faith of the church or some variant thereof (for example, God, the king and the ancient laudable customs, the latter not specified). Gray's point is that the oath was integral to the gathering of new forces as the rebellion spread westward across the north. At the same time the profession of allegiance made it difficult to see how the Pilgrims could effectively coerce the Henrician regime to respond as they wished.

Finally, Gray looks at the use of the sworn oath in heresy trials, particularly of the early evangelicals who responded positively to the new strands of religious thought coming from Lutheran Germany and the Netherlands and comes to the conclusion, already reached by such heresy hunters as Sir Thomas More, that many of them were quite prepared to swear falsely.

In a final chapter Gray steps back from his subtle analysis of the use and abuse of oaths in the latter years of Henry's reign—an analysis in which he is scrupulous to distinguish what can be known from the evidence or at best inferred—to ask what the long term consequence was for oath taking for the English people. It is an immensely interesting exercise that is frankly speculative, but nonetheless stimulating and not the least valuable part of this immensely thoughtful study.