Following ordination, Mallory served in Damaraland, first as Rector of Tsumeb, until 1962, and subsequently as Director of the Ovamboland Mission, also in South West Africa (Namibia), from 1963 to 1969, serving as Archdeacon of Ovamboland from 1964.
Doros crater is a differentiated igneous intrusion in the Damaraland region of Namibia to the northwest of the country's highest peak, Brandberg.
He saw in the German annexation of Damaraland and Namaqualand the first step in a design to secure for Germany territory stretching from ocean to ocean—a design which if executed would have been fatal to the British position in South Africa.