The Royal Berkshire Regiment (Princess Charlotte of Wales's) was a line infantry regiment of the British Army in existence from 1881 until 1959.
 The regiment was created in 1881, as the Princess Charlotte of Wales's (Royal Berkshire Regiment), by the amalgamation of the 49th (Princess Charlotte of Wales's) (Hertfordshire) Regiment of Foot and the 66th (Berkshire) Regiment of Foot.
 In 1921, it was renamed the Royal Berkshire Regiment (Princess Charlotte of Wales's).
The Siege of Mexico City was an 1867 military engagement in the French intervention in Mexico between Mexican Republican forces aided by the United States and Emperor Maximilian's troops aided by the French Empire and Austria-Hungary, encompassing in the siege of the city.
 It was the last armed conflict of the Second Mexican Empire and the fall of the city resulted in the transition of the Empire into the Republic led by Benito Juárez.
The Battle of Chihuahua or Recapture of Chihuahua City took place on March 24, 1866, in Chihuahua City, in Chihuahua State, Mexico, between elements of the Mexican Army of the Republic, led by Colonel Luis Terrazas, and French and Mexican troops in the service of the Second Mexican Empire during the Second French Intervention in Mexico.
 The attack on Chihuahua City, was launched by the Republicans at 9am against the imperial occupying forces, resulting in an imperial surrender of the city two hours later.
Princess Charlotte of Prussia (Viktoria Elisabeth Auguste Charlotte; 24 July 1860 – 1 October 1919) was Duchess Consort of Saxe-Meiningen as the wife of Bernhard III, the duchy's last ruler.
 Born at the "Neues Palais" in Potsdam, she was the second child and eldest daughter of Prince Frederick of Prussia, a member of the House of Hohenzollern who became Crown Prince of Prussia in 1861 and German Emperor in 1888.
 Through her mother Victoria, Princess Royal, Charlotte was the eldest granddaughter of the British monarch Queen Victoria and her consort Prince Albert of Saxe-Coburg and Gotha.
Manuel Orozco y Berra (8 June 1816 - 27 January 1881; He was born and died in Mexico City) was a Mexican historian and a member of the Mexican Academy of Language.
 "Orozco y Berra ranks as a major figure among 19th-century students of the Mexican Indian past."
 He produced a significant body of published work on Mesoamerican ethnohistory, and the government of the Second Mexican Empire charged him to create a new political division for the country.
Maximilian (Spanish: "Maximiliano"; born "Ferdinand Maximilian Joseph"; 6 July 1832 – 19 June 1867) was the only monarch of the Second Mexican Empire.
 He was a younger brother of the Austrian emperor Francis Joseph I.
 After a distinguished career in the Austrian Navy, he accepted an offer by Napoleon III of France to rule Mexico.
 France (along with the United Kingdom and Spain, who both withdrew the following year after negotiating agreements with Mexico's democratic government) had invaded Mexico in the winter of 1861, as part of the War of the French Intervention.
 Seeking to legitimize French rule in the Americas, Napoleon III invited Maximilian to establish a new Mexican monarchy for him.
 With the support of the French army, and a group of conservative Mexican monarchists hostile to the liberal administration of new Mexican President Benito Juárez, Maximilian traveled to Mexico.
 Once there, he declared himself Emperor of Mexico on 10 April 1864.
Princess Charlotte of Belgium, more commonly known as Carlota of Mexico (7 June 1840 – 19 January 1927) was a Belgian princess who became Empress of Mexico as the wife of Maximilian I of Mexico.
Charlotte Jones (1768 – 21 September 1847) was a British Miniature portrait painter.
 She was appointed 'Miniature Painter to the Princess Charlotte of Wales' from 1808 to the premature death of her patron.
 Princess Charlotte of Wales died shortly after failing to deliver a Royal heir.
 Jones' most memorable creation was a triptych that recorded the Princess's life.
The Mexican Empire (Spanish: "Imperio Mexicano" ) or Second Mexican Empire (Spanish: "Segundo Imperio Mexicano" ) was the name of Mexico under a limited hereditary monarchy declared by the Assembly of Notables on July 10, 1863, during the Second French intervention in Mexico.
 It was created with the support of Napoleon III of France, who attempted to establish a monarchist ally in the Americas.
 A referendum confirmed Austrian Archduke Ferdinand Maximilian, of the House of Habsburg-Lorraine, as Emperor Maximilian I of Mexico.
The office of Vice President of Mexico was created by the Constitution of 1824, and was finally abolished by the current Constitution of 1917.
 Many Mexican Vice Presidents acted as President during time between the end of the First Mexican Empire and the establishment of the Second Mexican Empire.

Question: Princess Charlotte of Belgium became the wife of which monarch of the Second Mexican Empire?
Answer: Maximilian I of Mexico