This chapter deals with the development of a conventionally armed nuclear-powered submarine, the subject of the Brazilian Navy’s main strategic programme, which began in 1979. Its origins lie in the context of the country’s efforts to combine the quest for mastery of nuclear technology, considered essential for independent energy supply, and the quest for a military power more capable of meeting the foreign policy challenges expected in the context of its predicted international rise, with the acquisition of a naval asset capable of reducing the strategic gap with developed countries. The first of these motivations has largely been achieved, while the second, which had a practical demonstration shortly afterwards, in 1982, with the decisive action of a British nuclear submarine in the Falklands War, has not yet had the desired final effect, raising the question that motivated this research: to what extent are factors related with military strategy driving the progress of the programme? Thus, this research sought to provide an answer, using a methodology that follows the historical method, which consists of studying events, processes, and institutions from the past in order to verify their influence on subsequent situations; and the functionalist method that seeks to analyse the actions and reactions of the components of the various processes. In doing so, it examines the conditioning factors of that moment and the current one from a technological and strategic perspective, as well as the relevant threats and alternatives for dealing with them at both times, concluding that the need to fill the gap to relevant navies and deter aggressors in the vast ocean persists in driving the programme. Within the academic domain, Defence is one of the areas of Political Science, and the programme has been treated there as a way of providing a naval means so important that it has been included in the National Defense Strategy since its first edition in 2008, and which in addition implies great benefits for the country’s industrial and technological development, especially in the nuclear field, but its need and relevance, as an effective resource for the nation’s security, is still little known. This chapter aims to fill this gap, and therein lies its academic importance.