Francis I, Holy Roman Emperor

Francis was born in Lunéville, Lorraine (now in France), the fourth and oldest surviving son of Leopold, Duke of Lorraine, and his wife Princess Élisabeth Charlotte d'Orléans. He was connected with the Habsburgs through his grandmother Eleonore, daughter of Emperor Ferdinand III. He was very close to his brother Prince Charles Alexander of Lorraine and sister Princess Anne Charlotte of Lorraine.

Emperor Charles VI favoured the family, who, besides being his cousins, had served the house of Habsburg with distinction. He had designed to marry his daughter Maria Theresa to Francis' older brother Léopold Clément, Hereditary Prince of Lorraine. On Leopold Clement's death, Charles adopted the younger brother as his future son-in-law. Francis was brought up in Vienna with Maria Theresa with the understanding that they were to be married, and a real affection arose between them.

At the age of 15, when he was brought to Vienna, he was established in the Silesian Duchy of Teschen, which had been mediatised and granted to his father by the Emperor in 1722. Francis succeeded his father as Duke of Lorraine in 1729. In 1731 he was initiated into freemasonry (Grand Lodge of England) by John Theophilus Desaguliers at a specially convened lodge in The Hague at the house of the British Ambassador, Philip Stanhope, 4th Earl of Chesterfield. During a subsequent visit to England, Francis was made a Master Mason at another specially convened lodge at Houghton Hall, the Norfolk estate of British Prime Minister Robert Walpole.

Maria Theresa arranged for Francis to become "Lord Lieutenant" (locum tenens) of Hungary in 1732. He was not excited about this position, but Maria Theresa wanted him closer to her. In June 1732, he agreed to go to the Hungarian capital, Pressburg (today's Bratislava).

When the War of the Polish Succession broke out in 1733, France used it as an opportunity to seize Lorraine, since France's chief minister, Cardinal Fleury, was concerned that, as a Habsburg possession, it would bring Austrian power too close to France.

A preliminary peace was concluded in October 1735 and ratified in the Treaty of Vienna in November 1738. Under its terms, Stanisław I, the father-in-law of King Louis XV and the losing claimant to the Polish throne, received Lorraine, while Francis, in compensation for his loss, was made heir to the Grand Duchy of Tuscany, which he would inherit in 1737.

In March 1736, the Emperor persuaded Francis, his future son-in-law, to secretly exchange Lorraine for the Grand Duchy of Tuscany. France had demanded that Maria Theresa's fiancé surrender his ancestral Duchy of Lorraine to accommodate the deposed King of Poland. The Emperor considered other possibilities (such as marrying her to the future Charles III of Spain) before announcing the engagement of the couple. If something were to go wrong, Francis would become governor of the Austrian Netherlands.

Elisabeth of Parma had also wanted the Grand Duchy of Tuscany for her son Charles III of Spain; Gian Gastone de' Medici was childless and was related to Elisabeth via her great-grandmother Margherita de' Medici. As a result, Elisabeth's sons could claim by right of being a descendant of Margherita.

Although fighting stopped after the preliminary peace, the final peace settlement had to wait until the death of Gian Gastone in 1737 to allow the territorial exchanges provided for by the peace settlement to go into effect.

On 31 January 1736, Francis agreed to marry Maria Theresa. He hesitated three times (and laid down the feather before signing). Especially his mother Élisabeth Charlotte d'Orléans and his brother Prince Charles Alexander of Lorraine were against the loss of Lorraine. On 1 February, Maria Theresa sent Francis a letter: she would withdraw from her future reign when a male successor to her father appeared.

Francis and Maria Theresa married on 12 February 1736 in the Augustinian Church, Vienna. The wedding was held on 14 February 1736. The (secret) treaty between the Emperor and Francis was signed on 4 May 1736. On 5 January 1737, instruments of cession were signed at Pontremoli between Spain and the Empire, with Spain ceding Parma, Piacenza and Tuscany to the Holy Roman Empire and the Empire recognizing Don Carlos of Spain as King of Naples and Sicily. On 10 January, the Spanish troops began their withdrawal from Tuscany and were replaced by 6,000 Austrians. On 24 January 1737, Francis received Tuscany from his father-in-law. Until then, Maria Theresa was Duchess of Lorraine.

Gian Gastone de' Medici, who died on 9 July 1737, was the second cousin of Francis (Gian Gastone and Francis' father Leopold were both great-grandchildren of Francis II, Duke of Lorraine), who also had Medici blood through his maternal great-great-grandmother Marie de' Medici, Queen consort of France and Navarre. In June 1737, Francis went to Hungary again to fight against the Turks. In October 1738, he was back in Vienna. On 17 December 1738, the couple travelled south, accompanied by his brother Charles, to visit Florence for three months. They arrived on 20 January 1739.

In 1744, Francis' brother Charles married a younger sister of Maria Theresa, Archduchess Maria Anna of Austria. In 1744, Charles became governor of the Austrian Netherlands, a post he held until his death in 1780.