In 1885 and 1890, respectively, the German Empire annexed the two independent African kingdoms of Rwanda and Burundi, forming the northwestern portion of what became the colony of German East Africa. This area was not effectively occupied or controlled by the colonial power, however. For the Belgians, the German presence in East Africa was a threat to the security of Congo. During World War I, some Belgian officials viewed the fighting in East Africa as an opportunity to expand Belgian territory. The Colonial Minister, Jules Renkin, favored a policy of trading territory gained in East Africa with the Portuguese, to expand the western Congo coast in a post-war settlement. A successful campaign in Africa was also seen as a way for the De Broqueville government to avenge the German invasion of Belgium.
At the outbreak of World War I in 1914, the northwestern region of German East Africa was the scene of fighting between German and Belgian forces from the Belgian Congo which bordered to the west. In April 1916, as part of the East African Campaign, Belgian-Congolese forces invaded Ruanda-Urundi and by September most of the west of German East Africa was under Belgian occupation while forces from the British Empire fought elsewhere in the colony.
The British conscripted 120,000 carriers to move Belgian supplies and equipment to Kivu (in the east of the Belgian Congo) between late 1915 and early 1916. The lines of communication in the Congo required around 260,000 carriers, which were barred by the Belgian government from crossing into German East Africa and Belgian troops were expected to live off the land. To avoid the plundering of civilians, loss of food stocks and risk of famine, with many farmers already conscripted and moved away from their land, the British set up the Congo Carrier Section of the East India Transport Corps (Carbel) with 7,238 carriers, conscripted from Ugandan civilians and assembled at Mbarara in April 1916. The Force Publique, started its campaign on April 18, 1916, under the command of General Charles Tombeur, Colonel Philippe Molitor and Colonel Frédérick Olsen and captured Kigali in Rwanda on May 6.
The German Askari in Burundi were forced to retreat by the numerical superiority of Force Publique and by June 17, Burundi and Rwanda were occupied. The Force Publique and the British Lake Force then started a thrust to capture Tabora, an administrative center of central German East Africa. They marched into German territory in three columns and took Biharamuro, Mwanza, Karema, Kigoma and Ujiji. After several days of battle, they secured Tabora on September 19. During the march, Carbel lost 1,191 carriers died or missing presumed dead, a rate of 1:7, which occurred despite the presence of two doctors and adequate medical supplies. To prevent Belgian claims on German territory in a post-war settlement, General J.C. Smuts ordered their forces to return to the Congo, leaving them as occupiers only in Rwanda and Burundi. The British were obliged to recall Belgian troops in 1917 and the two allies coordinated campaign plans.
The Treaty of Versailles divided the German colonial empire among the Allied nations. German East Africa was divided, with the vast majority of the territory, known as Tanganyika, going to the British and a small portion to Portugal. The western part of the colony, formally referred to as the Belgian Occupied East African Territories, was allocated to Belgium. In 1924, when the League of Nations issued a formal mandate granting Belgium full control over the area, the area officially became Ruanda-Urundi.
The Belgians issued stamps for the occupied territories in German East Africa from 1916 until 1922. The first general issue featured stamps of Belgian Congo overprinted Est Africain Allemande Occupation Belge/Duitsch Oost Afrika Belgische Bezetting in dark blue ink. In 1922, these were reissued with a surcharge of a new face value in red or black. In 1918, stamps of Belgian Congo were overprinted A.O. for ‘Afrique Orientale’. Local issues also appeared for Ruanda and Urundi, the overprints reading Ruanda and Urundi on black or blue ink. Stamps with similar overprints for several other locations in German East Africa — Karema, Kigoma and Tabora — were not officially authorized and aren’t recognized by the catalogs.
Scott #N17 was released in 1916, overprinted on a Belgian Congo 5-centime green and black stamp originally issued in 1915 (Belgian Congo Scott #60), portraying Port Matadi. Matadi was founded by Sir Henry Morton Stanley in 1879. It was strategically important because it was the last navigable port on the Congo River and therefore the furthest inland port in the Congo Free State. The mouth of the Congo forms one of Africa’s largest harbors. The construction of the Matadi–Kinshasa Railway (built between 1890 and 1898) made it possible to transport goods from deeper within Congo’s interior to the port of Matadi and the city became an important trading center. Portuguese and French West-African commercial interests influenced the city’s architecture and urban design which borrowed from the neighboring colonies in Angola and the Congo-Brazzaville. Today, it is the chief sea port of the Democratic Republic of the Congo and the capital of the Kongo Central province. It has a population of 245,862 (2004). Matadi is situated on the left bank of the Congo River 92 miles (148 km) from the mouth and 5 miles (8 km) below the last navigable point before rapids make the river impassable for a long stretch upriver.