February 1917 at the same time as Belgian forces were ordered to withdraw from the Tabora region by the British. While the Germans had begun the practice of conscripting labour from the Ruandans and Urundians during the war, this was limited since the German administration considered sustaining a local labour force logistically challenging. The Belgian occupation force expanded labor conscription; 20,000 men were drafted act as porters for the Mahenge offensive, and of these only one-third returned home. Many died due to malnourishment and disease. The new labour practices caused some locals to regret the departure of the Germans. League of Nations mandate, 1922–1946 The Treaty of Versailles in the aftermath of World War I divided the German colonial empire among the Allied nations. German East Africa was partitioned, with Tanganyika allocated to the British and a small area allocated to Portugal. Belgium was allocated Ruanda-Urundi even though this represented only a fraction of the territories already occupied by the Belgian forces in East Africa. Belgian diplomats had originally hoped that Belgian claims in the region could be traded for Portuguese territory in Angola to expand the Congo's access to the Atlantic Ocean but this proved impossible. The League of Nations officially awarded Ruanda-Urundi to Belgium as a B-Class Mandate on 20 July 1922. The mandatory regime was also controversial in Belgium and it was not approved by Belgium's parliament until 1924. Unlike colonies which belonged to its colonial power, a mandate was theoretically subject to international oversight through the League's Permanent Mandates Commission (PMC) in Geneva, Switzerland. Administratively, the mandate was divided into two pays, Ruanda and Urundi, each under the nominal leadership of a Mwami. The city of Usumbura and its adjoining townships were classified separately as centres extra‑coutumiers, while the pays were subdivided into territories. After a period of inertia, the Belgian administration became actively involved in Ruanda-Urundi between 1926 and 1931 under the governorship of Charles Voisin. The reforms produced a dense road-network and improved agriculture, with the emergence of cash crop farming in cotton and coffee. However, four major famines did ravage parts of the mandate after crop failures in 1916–1918, 1924–26, 1928–30 and 1943–44. The Belgians were far more involved in the territory than the Germans, especially in Ruanda. Despite the mandate rules that the Belgians had to develop the territories and prepare them for independence, the economic policy practised in the Belgian Congo