The Kingdom of Bulgaria also known as the Tsardom of Bulgaria existed from 1908 until 1946. It evolved from a Principality that existed from 1878 until 1908. Before 1878 it was part of the Ottoman Empire, since their defeat in the Bulgarian-Ottoman Wars in 1396.
Ferdinand of Saxe-Coburg and Gotha was Prince of Bulgaria from 7 July 1887 until 5 October 1908 when he declared himself the first King or Tsar of Bulgaria. He had married Marie Louise of Bourbon-Parma on 20 April 1893 with whom he had two sons and two daughters. Marie Louise died shortly after the birth of their fourth child in 1899 and was thus never Queen of Bulgaria. Shortly before declaring himself King, he married Eleonore Reuss of Köstritz, who then became the first Queen or Tsaritsa of Bulgaria.
The Balkan Wars and the subsequent First World War were hard on the Kingdom. During the First World War, Bulgaria entered into an alliance with Germany, Austria-Hungary and the Ottoman Empire but the following economic hardship made the war very unpopular with the public. The Russian Revolution made the public even more anti-monarchist and anti-war. In order to save his throne, King Ferdinand abdicated in 1918 in favour of his eldest son, Boris III, Tsar of Bulgaria. Boris married Princess Giovanna of Italy in 1930, and they had a son and a daughter together.
The economy was still a big problem in Bulgaria, and then it was hit by the Great Depression. A coup in 1934 led to Boris taking power for himself and ruling through puppet prime ministers. All opposition parties were banned, and Bulgaria allied itself with Nazi Germany and Fascist Italy. King Boris died suddenly in August of 1943, and he was succeeded by his six-year-old son, Simeon II. He was under the regency of Prince Kiril (his uncle), Bogdan Filov and Nikola Mikhov. By 1944, it was clear that Germany would be losing the war and Bulgaria’s cities were bombed by the allies. The Soviet Army entered the city of Sofia in September, and the next year Prince Kiril and several other high-ranking officials were executed on charges of war crimes. In a referendum held in 1946, the monarchy was abolished, and the young Tsar was sent into exile. The Kingdom of Bulgaria became the People’s Republic of Bulgaria, the Socialist Republic of Macedonia and the Socialist Federal Republic of Yugoslavia and the Kingdom of Bulgaria covered what is now Bulgaria, Greece, Romania, Macedonia, Serbia and Turkey.
King Simeon settled in Spain and married a Spanish aristocrat named Margarita Gómez-Acebo, and they have four sons and a daughter. He is still alive and even became the 48th Prime Minister of Bulgaria from 2001 and 2005.