Yes, they were a German colony a century ago. But the Germans have been replaced by The British and the French a hundred years ago.

The German Empire claimed the territory as the colony of Kamerun in 1884.
With the defeat of Germany in World War I, Kamerun became a League of Nations mandate territory and was split into French Cameroons and British Cameroons in 1919. [Wikipedia]

In the 1970s, you could still find very old people that could speak German in Cameroon, because they had learn the language at the beginning of the XXth century.