After Maximilian accepted the Mexican crown at the invitation of Napoleon III of France, Carlota sailed to Mexico ahead of him, taking in a tour of Yucatan (including the ruins of Uxmal) before sailing to Veracruz and then traveling inland to Mexico City. The couple's seat in Mexico City was Chapultepec Palace, a neo-Gothic fantasy on a hilltop on the edge of the city.
When Napoleon III withdrew his troops from Mexico and abandoned Maximilian to resist revolutionary forces by himself, Carlotta travelled to Europe, seeking assistance for her husband in Paris and Vienna and finally in Rome from the Pope. Her efforts failed, and she suffered a profound emotional collapse and never went back to Mexico. After the Mexicans executed her husband in 1867, her mental state deteriorated, and Carlota's brother, Prince Philippe, Count of Flanders, placed her in the hands of doctors who promptly declared her insane. She spent the rest of her life in seclusion, first at Miramar Castle near Trieste, Italy, and then at the Château de Bouchout in Meise, Belgium. She died in Meise on January 19, 1927. Some say she believed herself still to be the Empress in Mexico City until her death.
Carlota had no children with Maximilian, but in 1865 the imperial couple adopted Agustin de Iturbide y Green and Salvador de Iturbide y de Marzan, grandsons of Agustin I (Agustine de Iturbide y Aramburu), an earlier "Emperor of Mexico" who reigned from 1822 until 1823. They gave two-year-old Agustin the title of "His Highness, the Prince of Iturbide" -- similar imperial titles were accorded various members of the child's extended family -- and intended to groom him as heir to the throne. The explosive events of 1867, however, dashed such hopes, and after he grew to adulthood, Agustin de Iturbide y Green renounced all rights to the defunct Mexican throne, served in the Mexican army, and eventually established himself as a university professor in Washington, D. C.
Some have made the claim that Carlota had an illegitimate child by Alfred, Baron Van der Smissens, a Belgian colonel, giving birth at Brussels January 21, 1867. (This birthdate would indicate that the empress was pregnant when she sailed to Europe in support of her embattled husband.) According to some sources this child grew up to be General (Louis) Maxime Weygand (1867-1965). Weygand refused to either confirm or deny the persistent rumor, and his parentage remains uncertain. Some sources identify his mother as an unknown Pole and his father as either Leopold II of Belgium (Carlota's brother) or Maximilian. However, an eminent Belgian historian believed beyond doubt that Van der Smissens was indeed the father of General Weygand.