violation of the international order dates back much farther. Just war theory, over the centuries, held that a war fought for territorial aggrandizement was unjust, and that just wars are fought only for self-defense or in defense of allies. The philosophical basis for the criminalization of aggression derives from eighteenth-century theorist Emer de Vattel, although Vattel did not envision formal trials for aggression, simply the execution of wrongdoers. Early modern just war theorists conceived aggression as the first wrong committed against another country, rather than the first military strike. Hugo Grotius, often considered the founder of international law, saw the principle wrong in aggression in the violation of individual rights. In 1815, Napoleon was outlawed "as an Enemy and Disturber of the tranquillity of the World" in what was considered an "Exception to general rules of the Law of Nations". World War I and interwar After World War I, the prosecution of Kaiser Wilhelm II for aggression was proposed by the United Kingdom and France. In a speech on 11 November 1918, British prime minister David Lloyd George cited the loss of "the lives of millions of the best young men in Europe" and "the outrage upon international law which is involved in invading the territory of an independent country without its consent" as a crime for which someone should be held responsible. The proposed prosecution met with disapproval from the judiciary and was rejected by the United States. Instead, the League of Nations had the mandate of maintaining international peace. Interwar treaties criminalizing aggression were proposed but not ratified; there was no progress towards the criminalization of aggression. Aggressive war became progressively delegitimized, but was not considered illegal under international customary law. Although the 1928 Kellogg–Briand Pact did not contain any suggestion that war was criminal, it was cited as a precedent for the prosecution of German and Japanese leaders for waging aggressive wars after World War II. World War II Invasions during World War II led to new thinking on aggression. Soviet criminologist Aron Naumovich Trainin developed the ideas that were used to criminalize aggressive war, although he did not attract international attention until 1943. Others making similar proposals included Hersch Lauterpacht, Marcel de Baer, and . Trainin argued that although material and political responsibility rested with the state, criminal responsibility for aggressive war was vested in the individuals exercising authority. He blamed Adolf Hitler, his cabinet, government