 In 1874, together with the Woermann agent in Liberia, Wilhelm Jantzen, the two merchants founded their own company, Jantzen & Thormählen there.At the outbreak of World War I, French, Belgian and British troops invaded the German colony in 1914 and fully occupied it during the Kamerun campaign.The last German fort to surrender was the one at Mora in the north of the colony in 1916.