A war of aggression, sometimes also war of conquest, is a military conflict waged without the justification of self-defense, usually for territorial gain and subjugation. The phrase is distinctly modern and diametrically opposed to the prior legal international standard of "might makes right", under the medieval and pre-historic beliefs of right of conquest. Since the Korean War of the early 1950s, waging such a war of aggression is a crime under the customary international law. Possibly the first trial for waging aggressive war is that of the Sicilian king Conradin in 1268.