German presence in Africa posed no direct threat to the Belgian Congo; however, in 1914 a German gunboat sank a number of Belgian vessels on Lake Tanganyika. Congolese forces, under Belgian officers, fought German colonial forces in the Cameroons and seized control of the western third of German East Africa, advancing as far as the town at Tabora. The League of Nations in 1925 made Belgium the trustee of this territory (modern Rwanda and Burundi) as the mandate of Ruanda-Urundi.