[2][b] He took over as governor at a time of crisis in the colony, after a failed harvest in 1928 had led to starvation in eastern Rwanda, and the notables had opposed extending cultivation to the wet lowlands where they grazed their cattle.
[5] Postiaux toured Ruanda in April 1929, and remarked that the notables were demoralized by loss of authority and the threat of losing their cattle, while the people were suffering from a famine in which 35,000 to 40,000 had died.
[4] However, influenced by Bishop Classe, Postiaux wrote the following circular to the Ruanda residents on 2 October 1929:[6] A second abuse that ought equally to be forseen is that which consists in recognising natives of lower rank (bahutu or batwa) as having, even over goods produced by their labour or acquired by means of its fruits, only an incomplete right (usufruct, use, possession for life etc. )
By tolerating that a right; either wholly or in part, over wealth not created by them and without a true concession of land or breeding cattle, should pass into the hands of the Batusi chiefs or other notables, the authorities, would, in reality, be making themselves accomplices to an assumption of property rights which neither custom nor traditions suffice to justify or authorise...
If the native does not have any precise notion of these juridical ideas at the moment, it is incumbent on us to educate him on the matter, correcting his errors and moulding his mentality with perseverance and patience.
[4] On 28 May 1929 he wrote to the Minister of Colonies, "I can conclude that the government would not expose itself in Rwanda to any setback by relegating Musinga and providing him with a pension which should certainly not reach [...] the impressive sum represented by the 20th of the tax received in Rwanda and the tribute paid to him in kind by subjects over whom in reality he no longer exercises any authority other than that which we strive to retain: the most powerful provincial heads having virtually freed themselves and being perfectly suited to the new regime where the European authority has completely replaced […] the much less appreciated Mwami.
[9] In 1929 Postiaux called a "surprise meeting" of all the traditional chiefs of Rwanda in which he told them that all Rwandans must acquire an 8-page booklet that identified the holder.
[12] During his ninth term of service he replaced General Auguste Tilkens in January 1932 as acting Governor-General of the Belgian Congo.
He was appointed the delegate of the government in the Société des mines d'or de KiloMoto, and was made head of the Colonial School in Brussels.