Charlotte of Belgium, born princess of Belgium, became archduchess of Austria and empress of Mexico thanks to her marriage to Massimiliano I.
The only female daughter of Leopold I, King of the Belgians (1790-1865) and his second wife Luisa d'Orléans, Princess of Orléans (1812-1850), Carlotta was born in the Royal Palace of Laeken in Belgium. Carlotta had three brothers: Louis Philippe, who died in infancy, Leopold, who became Leopold II of Belgium and Philip, Count of Flanders, at the death of their father. She was also a cousin of Queen Victoria of the United Kingdom and her husband, Prince Albert, as well as Ferdinand II of Portugal.
His favorite grandmother Maria Amalia of Naples and Sicily, Queen of the French, was the consort of Louis Philippe of France, and a niece of Marie Antoinette. Maria Amalia was an intimate confidant of Carlotta, and on her wedding day in 1857, she wore a bracelet with a portrait of her miniature. Grandmother and nephew corresponded regularly, especially later when Carlotta was in Mexico.
When Carlotta was ten years old, her mother, Queen Luisa, died of tuberculosis and Carlotta was entrusted to the Countess of Hulste, a dear family friend. Although young, the princess had her home; but for a couple of weeks out of the year, Carlotta was staying in Claremont with Maria Amalia and the rest of her exile family.
His religious instruction was entrusted to the Redemptorist Victor-Auguste-Isidore Dechamps, brother of the then Minister of Foreign Affairs and, later, Bishop of Malines.
When Carlotta turned sixteen, Prince George of Saxony and King Peter, the latter candidate from Queen Victoria, were pretenders. In May 1856, the princess met in Brussels Archduke Ferdinand Maximilian of Austria (1832-1867), brother of the Austrian emperor Franz Joseph.
On 27 July 1857 Carlotta and Massimiliano married in Brussels. At the court of Vienna she was greatly appreciated by her mother-in-law Sofia of Bavaria, who saw in her the perfect example of wife for an Austrian archduke. Carlotta detested Empress Elisabeth (known as Sissi, the wife of Francesco Giuseppe). It was said that the Archduchess did not like the deep connection between the Empress and Maximilian, who were confident and shared the same taste for many things, especially because her sister-in-law was universally admired for her beauty and charm.
The archduke arrived in Milan on 6 September 1857 and resided there until 1859, when Maximilian was dismissed from his post. He had tried to rule the kingdom following liberal principles, but he clashed with the authority of Vienna.
Carlotta and Massimiliano retired for some time to private life, staying mainly in Trieste where they built the castle of Miramare, until, on October 3, 1863, a delegation of Mexican emigrants arrived to their residence to officially offer the archduke the crown of Mexico. In reality, the negotiations for this project had already been under way for more than two years. Napoleon III of France declared himself ready to support Massimiliano militarily as emperor, being interested in the formation of an area of Latin and Catholic culture in Central America, to counter the growing influence of the nascent United States of America. After a period of hesitations, on 10 April 1864 Massimiliano, having been informed of the result favorable to him of a referendum held in Mexico, accepted the "crown of the Mexican nation".
The new sovereigns made their solemn entry into Mexico City on June 12, 1864, finding a country disorganized and disturbed by insecurity and anarchy. It soon became apparent that it was a minority of the population who had appealed to them, foreign sovereigns, and not the majority. Despite everything, they began their reign with generous trust: the emperor initially managed to reconcile political parties, while the empress became popular visiting the city of Veracruz during a yellow fever epidemic.
Carlotta and Massimiliano had no children, but in 1865 the imperial couple adopted Agustín de Iturbide y Green and Salvador de Iturbide y Marzán - nephews of Agustín de Iturbide y Arámburu, a former emperor of Mexico (r 1822-23). They gave the two-year-old Agustín the title of "His Highness, The Prince of Iturbide" -similar titles were granted to various members of the extended family of the child, but never the intention to give him the throne, since not royal blood. Maximilian himself explained that it was all a farce to get from his brother, Archduke Charles Ludwig of Austria, that one of his sons became heir. The explosive events of 1867 disappointed the hopes of inheritance, and when he became an adult, Agustín renounced all the rights to the Mexican throne, served in the Mexican army, and finally settled as a professor at Georgetown University.
Some rumors insist that, in 1866, Carlotta had an affair with a Belgian officer, Colonel Alfred Van der Smissen and who gave birth to a son, Maxime Weygand, in Brussels on 21 January 1867. Weygand refused to confirm or deny the persistent rumors so his kinship remains uncertain. Weygand was a French military who fought in both I and World War II. 
The political situation degenerated quickly. On 9 July 1866, Carlotta left Mexico to return to Europe. She went to patronize her husband's cause first in Paris, then in Rome, without obtaining any results. Napoleon III, because of changes in the European political framework, abandoned every project concerning Mexico.
During his stay in Rome, where he went to ask for the help of Pope Pius IX, Carlotta gave the first signs of a serious mental imbalance. On October 7, his brother Filippo reached her and took her to Miramare, where he remained under the, cruel surveillance of the Austrian security agents until his brothers managed, with difficulty, to bring her back to Belgium.
On 19 June 1867 Massimiliano was shot by the Republicans in Querétaro.
After a brief moment of lucidity, in the period immediately following her husband's death, Carlotta finally sank into madness. He spent the rest of his life on the estate of Bouchout, purposely purchased for her by her brother Leopoldo, who was bound to his sister by a deep affection.