The House of Lorraine () was a noble house that ruled over the Duchy of Lorraine (1047–1431, 1473–1737) within the Holy Roman Empire, and also held other feudal domains, such as the County of Vaudémont, the Duchy of Bar, the Duchy of Guise, and various minor possessions. The cadet branch, headed by the Counts of Vaudémont, continued and reacquired the Duchy of Lorraine in 1473, thus establishing the junior ducal line, that ruled over Lorraine until 1737. Its cadet branch, the House of Guise, had a prominent position in political affairs of the Kingdom of France. In 1047, Adalbert, became Duke of Lorraine after his relative, the ruler of Verdun (of the House of Ardenne–Verdun) died. The House of Lorraine is a child house of the House of Ardenne, same as the House of Verdun.

By the marriage of duke Francis of Lorraine to Maria Theresa of Austria in 1736, and with the success in the ensuing War of the Austrian Succession (1740–1748), the House of Lorraine was joined to the House of Habsburg and became known as the House of Habsburg-Lorraine (). Francis, his sons Joseph II and Leopold II, and his grandson Francis II were the last four Holy Roman emperors from 1745 until the dissolution of the empire in 1806. The House of Habsburg-Lorraine inherited the Habsburg Empire, ruling the Austrian Empire and then Austria-Hungary until the dissolution of the monarchy in 1918.

Although its senior agnates are the dukes of Hohenberg, , the house was headed by Karl von Habsburg (born 1961), grandson of the last emperor Charles I.Gordon Brook-Shepherd. Uncrowned Emperor: the Life and Times of Otto von Habsburg. Continuum International Publishing Group, 2003. . pp. xi, 179, 216.

Ancestry Lineage of the House of Lorraine is certain since the 11th century, but due to the fragmentary nature of historical sources, reliable tracing of its older ancestry proved to be challenging within genealogical studies, particularly in light of various dynastic claims (direct or indirect connections with the Carolingians; common ancestry with the Habsburgs) posed by the junior ducal line during the early modern period.

A controversial origin The main two theories of the House's origin are:

the theory of Etichonid ancestry, which claims that Adalbert of Metz and his brother Gerard were descendants of the Nordgau branch of the Etichonid Dynasty, the same branch from which the House of Habsburg and the House of Zähringen could possibly descend; the theory of Gerardide ancestry, which claims that Adalbert and Gerard descended from the Matfridings which are thought to have been a branch of the Gerardides.

What is better documented is that in 1048 Emperor Henry III gave the Duchy of Upper Lorraine first to Adalbert of Metz and then to his brother Gerard, whose successors (collectively known as the House of Alsace or the House of Châtenois) retained the duchy until the death of Charles the Bold in 1431.

Certainties Based on documents dating from the 11th century, researchers are able to establish the two generations preceding Gerard of Alsace. The oldest certain generation is a sibling group shown at the top of the family chart below composed of Gerard, Adalbert and Adelaide:

Gerard, Count, probably of Metz, died between 1021 and 1033, married Eve, daughter of Count Sigefroid, ancestor of the Counts of Luxembourg. From this marriage were born two children: Sigfried, died between 1017 and 1020, and Berscinde, abbess of Remiremont;

Adelaide married Henry of Franconia, Count in Wormsgau, and is the mother of Emperor Conrad II the Salic and several other children;

Adalbert was Count of Metz, died in 1037. A donation dated June 12, 1037 in favor of the Abbey of Saint-Mathieu calls him dux and marchio Lotoringie. He married Judith who gave birth to a single son, named Gérard.

Gérard, son of Adalbert, died in 1045. He is called Count of Alsace in a charter of May 1038 where he puts an end to a dispute against the Abbey of Remiremont. He married a Gisèle, who gave birth to Adalbert, Duke of Lorraine in 1047, Gérard, Count of Metz, then Duke of Lorraine in 1047, Conrad, Adalberon, Beatrix, Odelric, Cuno, Oda, abbess of Remiremont from 1048 to 1071, Azelinus, Ida and Adelheid, as stated in the Notitiæ Fundationis Monasterii Bosonis-Villæ (Notice of the founding of the monastery of Bouzonville).

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Etichonid

The Etichonid origin was unanimously recognized from the 18th until the 20th century. For this reason, the marriage between Maria Theresa of Austria and Francis of Lorraine was seen at the time as the reunion of the two branches of the dynasty. The main proponents of this theory have been: Dom Calmet (1672 † 1757), Nicolas Viton de Saint-Allais (1773 † 1842) and more recently Michel Dugast Rouillé (1919 † 1987) and Henry Bogdan.

Gerardide-Matfriding The main proponents of the Gerardide-Matfriding theory are: Eduard Hlawitschka, George Poull and partially the Europäische Stammtafeln (which however does not take into account the kinship with the Girardides).

Renaissance & Modern

The Renaissance dukes of Lorraine tended to arrogate to themselves claims to Carolingian ancestry, as illustrated by Alexandre Dumas in the novel La Dame de Monsoreau (1846);See Chapter XXI. in fact, as seen above, the only evidence is of some interraltionships with the Carolingians, and some intermarriages with the Saxon Emperors and the Salian Emperors, but not so much as to give them any claims to the Imperial Crown, much less the Crown of France.

This did not stop the Bourbons in the Treaty of Montmartre in 1662 naming the non-Capetian House of Lorraine based on this supposed ancestry as next in line to the French throne after the Bourbons, in preference to the Capetian House of Courtenay, who would have been next by the Salic Law. Based on the terms of the accord, Louis XIV was given control of the Duchy of Lorraine, and Charles IV's family would become princes in the French royal family. However, it failed to take hold and Charles IV publicly repudiated it.

The house of Vaudémont continued to rule the independent duchies of Lorraine and Bar. However, Louis XIV's imperialist ambitions (which involved the occupation of Lorraine in 1669–97) forced the dukes into a permanent alliance with his archenemies, the Holy Roman Emperors from the House of Habsburg.

The final status of the duchy was only determined as part of the settlement of the War of Austrian Succession. As part of that, Francis Stephen, now Holy Roman Emperor and husband of Maria Theresa of Austria, Queen of Bohemia and Hungary, surrendered the Duchy of Lorraine to France, to be ruled by the former King of Poland, Stanisław Leszczyński, the father in law of Louis XV of France, during his lifetime, and then to be inherited by France. Francis Stephen and his heirs received the Grand Duchy of Tuscany, and all his wife's Habsburg lands (House of Habsburg-Lorraine).

Senior ducal line

The senior ducal line of the House emerged upon acquiring the Duchy of Upper Lorraine in the middle of the 11th century. As a loyal subject of the emperor Henry III, count Adalbert of Metz was appointed as Duke of Upper Lorraine in 1047, but died already in 1048. His brother Gerard (d. 1070) was appointed to succeed him as the new duke, and was in turn succeeded by his direct male descendants, who ruled over the Duchy up to 1431. During that period, the Duchy was one of the most prominent states of the Holy Roman Empire. In 1431, the duke Charles II died without sons or brothers. His closest male relative was Antoine, Count of Vaudémont, from the cadet branch of the House, but the Duchy of Lorraine passed to Charles' daughter Isabella, and her husband René I from the House of Valois-Anjou, thus initiating a Vaudémont-Angevine conflict ower Lorraine that lasted for years.

Junior ducal line

Since the extinction of the senior ducal line in 1431, the cadet branch of the House, headed by Counts of Vaudémont, took ower the family claims and aspirations, engaging in a series of disputes and conflicts with the Angevins over the possession of Lorraine. Those disputes were resolved in 1445, when count Frederick II of Vaudémont married Yolande, daughter of Isabella and René, thus establishing a close connection with the Angevine dukes of Lorraine. In 1470, Yolande's brother, duke John II of Lorraine died and was succeeded by his son Nicholas I, who died already in 1473, without male heirs. Thus, Yolande's and Frederick's son, count René of Vaudémont claimed the Duchy of Lorraine and succeeded in reacquiring it for the family, thus establishing the junior ducal line of the House, and later also adding to his titles that of the Duke of Bar (a domian within the French realm).Encyclopedia of the Middle Ages (ed. by André Vauchez). Routledge, 2000. . p. 1227.

During the entire period of their rule in Lorraine (1473–1737), dukes from the junior line were facing constant challenges from both the imperial authority, and the neighboring Kingdom of France, thus leading to a series of political and territorial disputes, conflicts, and arrangements with both sides. In 1542, the Treaty of Nuremberg was reached with the Emperor, securing a high degree of autonomy for the Duchy.

In the same time, the French Wars of Religion saw the rise of a cadet branch of the Lorraine ducal family, the House of Guise, which became a dominant force in French politics and, during the later years of Henry III's reign, was on the verge of succeeding to the throne of France.Robert Knecht. The Valois: Kings of France 1328–1589. Continuum International Publishing Group, 2007. . p. 214. Mary of Guise, mother of Mary, Queen of Scots, also came from this family. Under the Bourbon monarchy the remaining branch of the House of Guise, headed by the duc d'Elbeuf, remained part of the highest ranks of French aristocracy.

House of Habsburg‑Lorraine

After Emperor Joseph I and Emperor Charles VI failed to produce a son and heir, the Pragmatic Sanction of 1713 left the throne to the latter's yet unborn daughter, Maria Theresa. In 1736 Emperor Charles arranged her marriage to Francis of Lorraine who agreed to exchange his hereditary lands for the Grand Duchy of Tuscany (as well as the Duchy of Teschen from the Emperor).

At Charles's death in 1740 the Habsburg holdings passed to Maria Theresa and Francis, who was later elected (in 1745) Holy Roman Emperor as Francis I. The Habsburg-Lorraine nuptials and dynastic union precipitated, and survived, the War of the Austrian Succession. Francis and Maria Theresa's daughters Marie Antoinette and Maria Carolina of Austria became Queens of France and Naples-Sicily, respectively, while their sons Joseph II and Leopold II succeeded to the imperial title.

Apart from the core Habsburg dominions, including the triple crowns of Austria, Hungary and Bohemia, several junior branches of the House of Habsburg-Lorraine reigned in the Italian duchies of Tuscany (until 1737–1796, 1814–1860), Parma (1814–1847) and Modena (1814–1859). Another member of the house, Archduke Maximilian of Austria, was Emperor of Mexico (1863–67).

In 1900, Archduke Franz Ferdinand of Austria (then heir presumptive to the Austro-Hungarian throne) contracted a morganatic marriage with Countess Sophie Chotek. Their descendants, known as the House of Hohenberg, have been excluded from succession to the Austro-Hungarian crown, but not that of Lorraine, where morganatic marriage has never been outlawed. Nevertheless, Otto von Habsburg, the eldest grandson of Franz Ferdinand's younger brother, was universally regarded as the head of the house until his death in 2011.Brook-Shepherd also notes that morganatic alliances were not forbidden by ancient Magyar laws. See Brook-Shepherd 179. It was at Nancy, the former capital of the House of Vaudémont, that the former crown prince married Princess Regina of Saxe-Meiningen in 1951.

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