This dissertation examines German Protestant missionaries in Southwest Africa, their networks in Germany, and their notions of race. The Rhenish Mission Society was the dominant mission society in Southwest Africa until the early twentieth century. Its missionaries were the first European 'experts' on the Herero, Nama, Damra, and Koi-San. They took part in the German genocide of the Herero and Nama (1904-1907) and remained in Southwest Africa after Germany lost its colonies during World War I. After 1916, the Rhenish Mission struggled to regain support. With the onset of the National Socialist regime in 1933, some mission leaders and missionaries sought to curry favor with the Nazis and reshaped their depictions of Africans to fit racialist ways of thinking in the new Germany. Drawing on archival sources in Germany and Namibia, this study engages scholarly debates on continuity and change in German history. I show that Rhenish missionaries and their notions of Africans represent a significant strand of continuity that stretches from the Napoleonic period through the Nazi era and even beyond. The study begins with conservative religious reactions in the post-Napoleonic period and ends in 1936, three years into the Nazi regime, when missionaries in Africa seemed ever more distant from Germany with its focus on rearming in preparation for war in Europe. Across this period, the study identifies the intellectual and religious underpinnings of missionary notions and practice that found expression through the stories and reports missionaries sent home. Their writings reveal continuities in German history, even while they recounted developments in Africa and responded to changes back home. Although stationed on another continent, Rhenish missionaries were active in Germany. They used their narratives to raise support for overseas mission work and promote revivalist religion at home. As 'cultural mirrors,' missionary publications connected the German and the African through lessons in piety. They linked intellectual, religious, political, and racialist currents in Germany to produce potent ways of thinking about Africa. In the process, missionaries bound Christian faith to war, genocide, and racism and paved the way for Germans to accept, even expect, acts of extreme violence toward Africans.