Emperor Huizong of Song (7 June 1082 – 4 June 1135), personal name Zhao Ji, was the eighth emperor of the Song dynasty in China.
 He is also a very well-known calligrapher.
 Born as the 11th son of Emperor Shenzong, he ascended the throne in 1100 upon the death of his elder brother and predecessor, Emperor Zhezong, because Emperor Zhezong's only son died prematurely.
 He lived in luxury, sophistication and art in the first half of his life.
 In 1126, when the Jurchen-led Jin dynasty invaded the Song dynasty during the Jin–Song Wars, Emperor Huizong abdicated and passed on his throne to his eldest son, Emperor Qinzong, while he assumed the honorary title of "Taishang Huang" (or "Retired Emperor").
 The following year, the Song capital, Bianjing, was conquered by Jin forces in an event historically known as the Jingkang Incident.
 Emperor Huizong, along with Emperor Qinzong and the rest of their family, were taken captive by the Jurchens and brought back to the Jin capital, Huining Prefecture in 1128.
 The Jurchen ruler, Emperor Taizong, gave the former Emperor Huizong a title, Duke Hunde (literally "Besotted Duke"), to humiliate him.
 Emperor Huizong died in Wuguocheng after spending about nine years in captivity.
Liu Penzi (; born 10 AD) was a puppet emperor placed on the Han dynasty throne temporarily by the Red Eyebrows (Chimei) rebels after the collapse of the Xin dynasty, from 25 to 27 AD.
 Liu Penzi and his two brothers were forced into the Red Eyebrows as child soldiers.
 When the Red Eyebrows submitted to the new Emperor Gengshi of Han, his older brother Liu Gong fled to support the new emperor.
 Later, the Red Eyebrows rose again in rebellion and chose Liu Penzi as emperor.
 When they took Chang'an, Liu Penzi was officially Emperor of China, but he never had actual powers.
 When Liu Xiu definitively defeated the Red Eyebrows, he spared the 17 year old puppet emperor.
Virginia Oldoini, Countess of Castiglione (22 March 1837 – 28 November 1899), better known as "La Castiglione", was born to an aristocratic family from La Spezia.
 She was a 19th-century Italian aristocrat who achieved notoriety as a mistress of Emperor Napoleon III of France.
 She was also a significant figure in the early history of photography.
Dorgon (Manchu: , literally "badger"; 17 November 1612 – 31 December 1650), formally known as Prince Rui, was a Manchu prince and regent of the early Qing dynasty.
 Born in the Aisin Gioro clan as the 14th son of Nurhaci (the founder of the Qing dynasty), Dorgon started his career in military campaigns against the Ming dynasty, Mongols and Koreans during the reign of his eighth brother, Huangtaiji, who succeeded their father.
 After Huangtaiji's death in 1643, he was involved in a power struggle against Huangtaiji's eldest son, Hooge, over the succession to the throne.
 Both of them eventually came to a compromise by backing out and letting Huangtaiji's ninth son, Fulin, become the emperor; Fulin was installed on the throne as the Shunzhi Emperor.
 Dorgon served as Prince-Regent from 1643–1650, throughout the Shunzhi Emperor's early reign.
 In 1645, he was given the honorary title "Emperor's Uncle and Prince-Regent"; the title was changed to "Emperor's Father and Prince-Regent" in 1649.
 Under Dorgon's regency, Qing forces occupied Beijing, the capital of the fallen Ming dynasty, and gradually conquered the rest of China in a series of battles against Ming loyalists and other opposing forces around China.
 Dorgon also introduced the policy of forcing all Han Chinese men to shave the front of the heads and wear their hair in queues just like the Manchus.
 He died in 1650 during a hunting trip and was posthumously honoured as an emperor even though he was never an emperor during his lifetime.
 A year after Dorgon's death, however, the Shunzhi Emperor accused Dorgon of several crimes, stripped him of his titles, and ordered his remains to be exhumed and flogged in public.
 Dorgon was posthumously rehabilitated and restored of his honorary titles by the Qianlong Emperor in 1778.
Count Semyon Romanovich Vorontsov (Russian: Семён Романович Воронцо́в ; 26 June 1744 – 9 July 1832) was a Russian diplomat from the aristocratic Russian Vorontsov family, whose siblings included Alexander Vorontsov, Elizaveta Vorontsova and Yekaterina Vorontsova-Dashkova.
Conrad of Antioch (Italian: "Corrado d'Antiochia" ; born 1240/41, died after 1312) was a member of the imperial Staufer dynasty and a nobleman of the Kingdom of Sicily.
 He was the eldest son of Frederick of Antioch, imperial vicar of Tuscany, and Margherita di Poli.
 He was thus a grandson of the Emperor Frederick II (reigned 1220–50), a nephew of King Manfred of Sicily (1258–66) and cousin of King Conradin (1266–68).
 His surname, which is contemporary, comes from his paternal grandmother, a mistress of Frederick II, who was from Antioch.
 He may be called "Conrad I" to distinguish him from his descendants with the same given name.
Serapia was a Roman saint, a slave and martyr, also called Seraphia or Seraphima of Syria.
 Saint Serapia was born at Antioch in the late 1st century, of Christian parents who, fleeing the persecution of Emperor Hadrian, went to Italy and settled there.
 When her parents died, Serapia was sought in marriage by many, but having resolved to consecrate herself to God alone, she sold all her possessions and distributed the proceeds to the poor.
 Then she sold herself into voluntary slavery, and entered the service of a Roman noblewoman named Sabina.
 The piety of Serapia, her love of work, and her charity soon gained the heart of her mistress, who became a Christian.
 She died in 119 .
Peter III (21 February 1728 – 17 July [O.S. 6 July] 1762 ) (Russian: Пётр III Фëдорович, "Pyotr III Fyodorovich" ) was emperor of Russia for six months in 1762.
 He was born in Kiel as Karl Peter Ulrich, the only child of Charles Frederick, Duke of Holstein-Gottorp, (the child of Hedvig Sophia of Sweden, sister of Charles XII), and Anna Petrovna, (the elder surviving daughter of Peter the Great).
 The German Peter could hardly speak Russian and pursued a strongly pro-Prussian policy, which made him an unpopular leader.
 He was deposed and possibly assassinated as a result of a conspiracy led by his German wife Princess Sophie Friederike Auguste von Anhalt-Zerbst-Dornburg, who succeeded him to the throne as Catherine II.
 His death could also have been the result of a drunken brawl with his bodyguard when he was being held captive after Catherine's coup.
Elizaveta Romanovna Vorontsova (Russian: Елизавета Романовна Воронцова ) (13 August 1739 – 2 February 1792) was a mistress of Emperor Peter III of Russia.
 During their affair, Peter was rumored to have intentions of divorcing his wife Catherine (the future empress) to marry Vorontsova.
Léonie Léon (1838–1906) was the French mistress of statesman Léon Gambetta.
 Born Marie-Léonie in Paris on 6 November 1838, she was the daughter of a French artillery officer.
 She was educated at the Louvencourt Sisters convent school in Dunkirk.
 Following the death of her father in the Charenton asylum in 1860, Léon took Louis-Alphonse Hyrvoix, who was in charge of Emperor Napoleon III's security, as a lover.
 She gave birth to Alphonse Léon, Hyrvoix's son, in Bordeaux on 5 February 1865.

Question: In what year was the emperor of whom Elizaveta Vorontsova was a mistress born?
Answer: 1728