The Treaty of Trianon was the peace agreement of 1920 to formally end World War I between most of the Allies of World War I and the Kingdom of Hungary, the latter one of the successor states to Austria-Hungary. The treaty regulated the status of an independent Hungarian state and defined its borders. The treaty left Hungary as a landlocked state covering , only 28% of the that had constituted the pre-war Kingdom of Hungary (the Hungarian half of the Austro-Hungarian monarchy). Its population was 7.6 million, only 36% of the pre-war kingdom's population of 20.9 million. The areas that were allocated to neighbouring countries in total (and each of them separately) possessed a majority of non-Hungarian population, but 31% of Hungarians (3.3 million) were left outside of post-Trianon Hungary. Five of the pre-war kingdom's ten largest cities were drawn into other countries. The treaty limited Hungary's army to 35,000 officers and men, while the Austro-Hungarian Navy ceased to exist.