Neuilly, Treaty of, November 27, 1919, the peace treaty signed by defeated Bulgaria and the World War I victors. It was signed at Neuilly-sur-Seine, France, a suburb of Paris. Bulgaria ceded its Thracian outlet to the Aegean Sea to Greece, and some territory in Macedonia to Yugoslavia; it also agreed to pay reparations, limit the size of its army, and surrender most of its war matériel.