The Portuguese authorities balanced missionary and political dynamics as they sought to strengthen their claims over African territories in an imperial and colonial world that was becoming increasingly internationalized. This book sets out to investigate how missionary authorities reacted to national challenges from the monarchical and republican regimes, and rising competition within the Catholic world, as well as the "Protestant threat", at the international level. To what degree were religious and missionary projects a political instrument? Was this situation similar in other colonial empires? The 1890 British Ultimatum was part of a process of conflicting religious competition in Africa (among Catholics, and between Catholics and Protestants) in parallel with inter-imperial disputes. The Portuguese authorities saw missionary presence as a potentially useful political weapon, but it cut two ways: in favour of or against its colonial rule. Foreigner missionaries in what was considered the Portuguese empire were viewed as "threats" since they could act as political bridgeheads for other imperial powers or could influence the native populations against Portuguese colonial presence. Anglo-Portuguese competition in Africa, the "native" uprisings against Portuguese rule, the attempts to negotiate a concordat with the Holy See, the Portuguese First Republic, and the aftermath of the First World War had powerful effects on the direction of Portuguese statehood, and were reflected in substantive internal debate and political disagreement. The overview of missionary experience in the Portuguese empire provided in this book is a major contribution to the international historiography of missions and empires.