Scarce in West Africa, cowries were purchased cheaply in the Seychelles where they were common and sold at great profit to African middlemen involved in the slave trade (Zanzibar was the main slave port in East Africa.

The cowry money was also currency in the to and fro trade of commodities and products, especially linen between Zanzibar and Hamburg.

In 1859 William O'Swald negotiated with Majid ibn Sa'id, the Sultan of Zanzibar, a commercial contract for the Hanseatic cities of Hamburg, Lübeck and Bremen, which had great influence in interior eastern Africa.

In the following years using his position as Honorary Consul in Zanzibar he established new branches of the company in Madagascar, the Somali Coast and the German Protectorate in East Africa.

O'Swald was also "praeses" (head) of the deputation for trade and shipping (a mixed commission of experts and officials) in the administration of Hamburg.