Wilhelm Rickmann studied at the Tierärztliche Hochschule in Berlin and was awarded a doctoral degree in veterinary science in 1894. That same year he came to German South West Africa (now Namibia) as a government official and took part in battles against the Witbooi tribe during August to November, earning a military decoration.
Rickman was probably the first qualified veterinarian to work in the territory. Already in 1895 he published an article on horse sickness, "Pferdezucht im Schutzgebiete", in the Deutsche Kolonialblatt. In 1898, following a visit to the territory by Dr P.M.J. Kohlstock*, a lungsickness station at Gammams, near Windhoek, was transformed into a centre for producing rinderpest vaccine. Rickmann was put in charge and successfully combated the rinderpest epidemic that had swept over southern Africa during 1896 and 1897. For this work he was awarded the Königlicher Kronenorden by the German government. Gammams developed into a veterinary bacteriological institute where he performed research on stock diseases. From 1902 his post was that of chief professional officer for cattle-breeding and veterinary services. He combated diseases such as lungsickness, malignant catarrhal fever, scab, gall sickness, and tapeworm disease, but also organised cattle breeding and appointed additional veterinarians to attend to the needs of the farming community. Under his direction horse breeding was initiated at Nauchas [either 100km north of Keetmanshoop, or 90 km west-south-west of Rehoboth] to supply mounts for the police and military. However, about half the foals were lost each year to horse sickness. In 1903 he contributed another article to the Deutsche Kolonialblatt, "Die Bandwurmplage in Deutsch-Südwestafrika", dealing with a tapeworm plague. From 3 to 5 December that year he attended the "Conference on diseases among cattle and other animals in South Africa" in Bloemfontein, as the representative for German South West Africa. After the conference he spent a week with Arnold Theiler* at Onderstepoort.
During the Herero uprising in 1904 Rickmann served as an officer and was awarded the Roter Adlerorden. The institute at Gammams was plundered and destroyed during the uprising, but was rebuilt in 1905. Rickmann retired on pension in 1907 as a result of poor health and returned to Germany. The next year he published an important book, Tierzucht und Tierkrankheiten in Deutsch-Südwestafrika (Berlin, 1908). Based on his experience in the territory, it was aimed at veterinarians, farmers and breeders. That same year he also wrote an article, "Die Rotzkrankheit in Deutsch-Südwestafrika", on glanders, for the Berliner Tierarzliche Wochenschrift. In 1910 he submitted his inaugural dissertation at Bern, entitled Untersuchungen über die wirksamheit des Bacillus suipestifer und vershschiedener anti-sera... (Berlin, 1910, 60p). Soon thereafter Professor R. Ostertag, who conducted a tour of inspection in Namibia around 1911, spoke of Rickmann's work with great appreciation.