the Great Union Day, that is a national holiday. The Romanian expression România Mare (Great or Greater Romania) refers to the Romanian state in the interwar period and to the territory Romania covered at the time. At that time, Romania achieved its greatest territorial extent, almost ), including all of the historic Romanian lands. Most of the claimed territories were granted to the Old Kingdom of Romania, which was ratified in 1920 by the Treaty of Trianon that defined the new border between Hungary and Romania. The union of Bucovina and Bessarabia with Romania was ratified in 1920 by the Treaty of Versailles. Romania also acquired Southern Dobruja territory called "The Quadrilateral" from Bulgaria as a result of its participation in the Second Balkan War in 1913. As a result of the peace treaties, most regions with clear Romanian majorities were merged into a single state. It also led to the inclusion of sizable minorities, including Magyars (ethnic Hungarians), Germans, Jews, Ukrainians and Bulgarians—about 28% of the country's population. National minorities were recognized by the 1923 Constitution of Romania and supported by laws; they were represented in Parliament and several of them created political parties, although a unique standing of minorities with autonomy on a wide basis, provided for at the Great National Assembly of Alba Iulia on 1 December 1918, was not fulfilled. The Romanian expression România Mare (literal translation "Great Romania", but more commonly rendered in English: "Greater Romania") generally refers to the Romanian state in the interwar period, and by extension, to the territory Romania covered at the time. Romania achieved at that time its greatest territorial extent (almost ). At the 1930 census, there were over 18 million inhabitants in Romania. The resulting "Greater Romania" did not survive World War II. Until 1938, Romania's governments maintained the form, if not always the substance, of a liberal constitutional monarchy. The National Liberal Party, dominant in the years immediately after World War I, became increasingly clientelist and nationalist, and in 1927 was supplanted in power by the National Peasants' Party. Between 1930 and 1940 there were over 25 separate governments; on several occasions in the last few years before World War II, the rivalry between the fascist Iron Guard and other political groupings approached the level of a civil war. Upon the death of King Ferdinand in 1927, his son, Prince Carol, was prevented from succeeding him because