One of the first parties to call for Burundian independence was the Union pour le Progres National (UPRONA) that united the Burundian ethnic groups in a common call for independence from Belgium. Especially appalled by the ethnic violence and instability in neighboring Rwanda, the country called for ethnic unity, something that had largely been absent during the colonial era. The Belgians, opposing such independence, supported the allied Parti Démocrate Chrétien (PDC), but at the time of elections, UPRONA won the majority vote and the country ultimately gained independence in 1962 as a monarchy where the king, holding executive power, would share legislative power with the Parliament. Since independence, Burundi has seen extensive violence between members of the Hutu and Tutsi ethnic groups. Burundi's post-colonial ethnic tensions have especially been compared to those in Rwanda, which saw similar ethnic tension between Hutu and Tutsi flare up into violence on several occasions, notably during the Rwandan genocide. The unity of UPRONA did not last long as its leading moderate Prince and then Prime Minister Rwagasore, was assassinated by opposition. A power vacuum soon followed that pitted Hutus and Tutsis against one another and capitalized on ethnic politics rather than the previously sought national unity. With Burundi an independent state now, the ethnic groups quickly sought to advance their own self-interests. Tutsi elites began to use their influence and power coming from the colonial era to advance their ranks in Burundian politics while excluding Hutus, and also gained control of the military. The monarchy, then under Mwambutsa, was the sole source of power and resorted to ease the potential ethnic tensions by balancing the Hutu and Tutsi representation in successive governments up until 1965.This balancing act was not necessarily appreciated by both sides leading to further escalation of tensions. Tensions peaked in 1965, when the king appointed Hutu prime minister Ngendendumwe, who was assassinated by a Tutsi extremist. The mwami then resorted to elections anew, only to go against the Hutu majority results and appoint Tutsi  Leopold Biha as Prime Minister. This then led to violence and revolt by many Hutu elites and politicians, leading to Tutsi retaliation and  violent suppression of it by the Tutsi-majority army led by Captain Michel Micombero. Soon after, Hutus across the country reacted, resulting in the killing of around 500 Tutsis.