Charles I of Austria in the context of "House of Lorraine"

The Kingdom of Hungary, referred to retrospectively as the Regency, the Horthy era, the Horthy regime, and Horthyist Hungary, existed as a country from 1920 to 1946 under the rule of Miklós Horthy for the most of its existence, who officially represented the Hungarian monarchy after a period of revolutions and the counter-revolution as the Regent of Hungary. In reality there was no king, and attempts by King Charles IV to return to the throne shortly before his death were prevented by Horthy.

Horthy came to power after supressing the Hungarian Soviet Republic during the period of White Terror, installing an authoritarian political system relying on the traditional economic elites and bureaucracy. Hungary under Horthy was characterized by its conservative, nationalist, and fiercely anti-communist character; some historians have described this system as para-fascist. The government was based on an unstable alliance of conservatives and right-wingers; while conservatism was predominant in the 1920s, afterwards Horthy manoeuvered between conservatives and the radical right with fascist leanings. Foreign policy was characterized by revisionism — the total or partial revision of the Treaty of Trianon, which had seen Hungary lose over 70% of its historic territory along with over three million Hungarians, who mostly lived in the border territories outside the new borders of the kingdom, in the Kingdom of Romania and the newly created states of Czechoslovakia and the Kingdom of Serbs, Croats and Slovenes (in greatly enlarged Romania there also remained a significant Hungarian population in Székely Land). Republican Austria, the successor of the former other half of the dual monarchy also received some minor territory from Hungary. Thus the post-1918 kingdom can be described as a rump state. Hungary's interwar politics were dominated by a focus on the territorial losses suffered from this treaty, with the resentment continuing until the present. After a period of international isolation in the 1920s, it began maintaining ties with Fascist Italy and Nazi Germany.

The emperor of Austria (German: Kaiser von Österreich, Latin: Imperator Austriae) was the ruler of the Austrian Empire and later the Austro-Hungarian Empire. The hereditary imperial title and office was proclaimed in 1804 by Francis II, Holy Roman Emperor, a member of the House of Habsburg-Lorraine, and continually held by him and his heirs until Charles I relinquished power in 1918.

The emperors retained the title of Archduke of Austria. The wives of the emperors held the title empress, while other members of the family held the titles of archduke or archduchess.

The Holy Crown of Hungary (Hungarian: Szent Korona [ˈsɛnt ˈkoronɒ], Latin: Sacra Corona), also known as the Crown of Saint Stephen, named in honour of Saint Stephen I of Hungary, was the coronation crown used by the Kingdom of Hungary for most of its existence; kings were crowned with it since the twelfth century. The Crown symbolized the King's authority over the Lands of the Hungarian Crown, and it was a key mark of legitimacy. Through the history of Hungary, more than fifty kings were crowned with it, with the last being Charles IV in 1916. The only kings not crowned were Wladyslaw I, John Sigismund Zápolya, and Joseph II.

The enamels on the crown are mainly or entirely Byzantine work, presumed to have been made in Constantinople in the 1070s. The crown was presented by the Byzantine Emperor Michael VII Doukas to the King Géza I of Hungary; both are depicted and named in the Greek language on enamel plaques in the lower crown. However, in popular tradition the Holy Crown was thought to be older and of Papal provenance, dating to the time of the first King Stephen I of Hungary crowned 1000/1001. It is one of two known Byzantine crowns to survive, the other being the slightly earlier Monomachus Crown in the Hungarian National Museum, which may have had another function. The Holy Crown has probably been remodelled using elements of different origins. The date assigned to the present configuration of the Holy Crown is most commonly put around the late 12th century. The Hungarian coronation regalia consists of the Holy Crown, the sceptre, the orb, and the mantle. The orb has the coat of arms of Charles I (1310–1342).

Karl von Habsburg (given names: Karl Thomas Robert Maria Franziskus Georg Bahnam; born 11 January 1961) is an Austrian politician and the head of the House of Habsburg-Lorraine, the former royal house of the defunct Austro-Hungarian thrones. As a citizen of the Republic of Austria, his legal name is Karl Habsburg-Lothringen.

Karl is the son of Otto von Habsburg and Regina von Sachsen-Meiningen, and the grandson of the last Austro-Hungarian emperor, Charles I. He is head and sovereign of the Austrian Order of the Golden Fleece. Karl Habsburg served as a member of the European Parliament for the Austrian People's Party (1996–1999). He is known for being pro-European and is also an advocate for the Pan-European movement.

Miklós Horthy de Nagybánya (18 June 1868 – 9 February 1957) was a Hungarian admiral and statesman who was the regent of the Kingdom of Hungary during the interwar period and most of World War II, from 1 March 1920 to 15 October 1944.

Horthy began his career as a sub-lieutenant in the Austro-Hungarian Navy in 1896 and attained the rank of rear admiral by 1918. He participated in the Battle of the Strait of Otranto and ascended to the position of commander-in-chief of the Navy in the final year of World War I. Following mutinies, Emperor-King Charles I and IV appointed him a vice admiral and commander of the Fleet, dismissing the previous admiral. During the revolutions and interventions in Hungary from Czechoslovakia, Romania and Yugoslavia, Horthy returned to Budapest with the National Army. Subsequently, the Diet of Hungary offered him the position of Regent of Hungary, while the House of Habsburg and Hungarian monarchy was formally dethroned.

After Miklós Horthy was chosen Regent of Hungary on 1 March 1920, Charles I of Austria, who had reigned in Hungary as Charles IV, made two unsuccessful attempts to retake the throne. His attempts are also called the "First" and "Second Royal coups d'état" (Hungarian: első és második királypuccs) respectively.