Mbonyumutwa was of Hutu ethnicity and was respected by the population both before and after his presidency. On 1 November 1959, while serving as a "sous-chef" (equivalent to a district mayor today), he was assaulted by a group of Tutsi youth in Byimana in Southern Province. This incident triggered the "social revolution" of November 1959, which eventually brought down the monarchy while driving hundreds of thousands of Rwandan Tutsi into decades-long exile.