THE 1950s AND EARLY 1960s have been called the Golden Age of Nuclear Strategy, an era in which civilian scholars and practitioners, principally Americans but French theorists as well, dominated strategic thought. These theorists--physicists, military officers, economists, and political scientists--defined nuclear strategy and the potentiality for Armageddon with a detached, cold calculus, granting negligible consideration to the moral implications of such a war. Ostensibly, the argument over nuclear strategy and its abstract constructs ceased when the four nuclear powers adapted to mutual assured destruction as an established element of the Cold War environment. Nearly two decades later, however, after President Jimmy Carter withdrew the SALT II Treaty from U.S. Senate ratification, and President Ronald Reagan announced plans to introduce intermediate-range nuclear weapons into Western Europe, the debate was revitalized. It gathered energy from the dissenting voices of the European nuclear freeze and disarmament movements, but also from the U.S. Catholic bishops' 1983 Pastoral Letter on War and Peace. In this document, the bishops examined the key issues of modern warfare, including nuclear weapons and deterrence. It is at this point that Michael Quinlan, a Jesuit-educated, senior British defense official entered the public discussion. He would remain a potent elucidator of the logic of nuclear weapons as it related to British national interests throughout his tenure as permanent secretary, the highest civil service rank, at the Ministry of Defence under Prime Minister Margaret Thatcher and continuing until his death in 2009. This article explores Quinlan's role as a significant thinker on nuclear strategy and international security by examining his arguments for the possession and potential use of nuclear weapons within the just war tradition. Some critics contend that Quinlan entered the civic contest primarily to uphold British defense policy by arguing that its nuclear weapons provided a second centre of (in addition to the United States) that deterred the Soviet leadership from believing it could risk a nuclear attack on Europe without prompting U.S. retaliation. However, such a narrow perspective removes an important impetus to Quinlan's actions: the tension that existed in his conscience. For Quinlan, the argument was not solely about nuclear strategy, the employment of these weapons, and the ethical norms associated with targeting. As a member of British strategic culture, he also needed to reduce the conflict between his temporal identity as a senior civil servant (defender of the realm) and his spiritual identity as a devout Roman Catholic. Moreover, his profound identification with these two cultures, while recognized but not fully examined, (1) accounts for his decision to act as a bridge between them through his personal correspondence as well as his writings and speeches to various public audiences. Thus, Quinlan stands astride British strategic culture and Catholicism. To interpret his thinking on the role of the state, deterrence, and the morality of nuclear weapons first requires an understanding of these two cultures. Cultures and Tradition C.P. Snow, the British scientist and novelist who served in several high-ranking civil service positions, declared in his 1959 Rede lecture the existence of two prominent cultures in modern society, science and humanities, and lamented the communication barrier that existed between them. He argued that this obstruction diminished both sides and impeded efforts to solve the problems of the world. (2) Quinlan, who represented a new generation of intellectuals, decried the strains between two other cultures of which he was part, ones more venerable and ancient than the ones Snow identified: the temporal and the spiritual or more specifically, that of the political order and Christianity. Quinlan considered the Ministry of Defence (MoD) as his home, and his 1981 transfer to the treasury after nearly three decades of service in the defense establishment resulted in considerable vexation; he characterized the reassignment as a deportation. …