Wikipedia
The term ''' Debellatio ' (also debellation) ( Latin "defeating, or the act of conquering or subduing", literally, "warring'' (the enemy) down", from Latin bellum "war") designates the end of a war caused by the absolute destruction of one combatant such as of Palestrina by Pope Boniface VIII.
In some cases debellation ends with a complete dissolution and annexation of the defeated state into the victor's national territory, as happened at the end of the Third Punic War with the defeat of Carthage by Rome in the 2nd century BC. The Prussian conquest, dissolution and annexation of the Kingdom of Hanover in 1866 is an example from the modern world.
The unconditional surrender of the Third Reich—in the strict sense only the German Armed Forces—at the end of World War II was at the time accepted by most authorities as a case of debellatio as it ended with the complete breakup of the German Reich, including all offices, and two German states being created in its stead (the Federal Republic of Germany and the German Democratic Republic). Other authorities have argued against that, as most of the territory that made up Germany before the Anschluss was not annexed, and the population still existed, the vestiges of the German state continued to exist even though the Allied Control Council governed the territory; and that eventually a fully sovereign German government resumed over a state that never ceased to exist. The Federal Republic of Germany sees itself as the legal successor of the Third Reich.
Similarly, the breakaway state of Tamil Eelam, which once controlled much of northern Sri Lanka, was completely destroyed at the end of the Sri Lankan Civil War in 2009, and all of the leadership killed.