Christian IX (8 April 1818 – 29 January 1906) was King of Denmark from 15 November 1863 until his death in 1906. From 1863 to 1864, he was concurrently Duke of Schleswig, Holstein and Lauenburg. He became one of the most influential monarchs of 19th-century Europe through the dynastic marriages of his children, earning the sobriquet "father-in-law of Europe". Because many later European monarchs descended from him, he is also sometimes informally described as the "grandfather of Europe".
A younger son of Frederick William, Duke of Schleswig-Holstein-Sonderburg-Glücksburg, Christian grew up in the Duchy of Schleswig as a prince of Schleswig-Holstein-Sonderburg-Glücksburg, a junior branch of the House of Oldenburg, which had ruled Denmark since 1448. Although having close family ties to the Danish royal family, he was originally not in the immediate line of succession to the Danish throne. Following the early death of his father in 1831, Christian grew up in Denmark and was educated at the Military Academy of Copenhagen. After unsuccessfully seeking the hand of Queen Victoria of the United Kingdom in marriage, he married his double second cousin, Princess Louise of Hesse-Kassel, in 1842.
In 1852, Christian was chosen as heir presumptive to the Danish throne in light of the expected extinction of the senior line of the House of Oldenburg. Upon the death of King Frederick VII in 1863, Christian (who was Frederick's second cousin and husband of Frederick's paternal first cousin, Louise of Hesse-Kassel) acceded to the throne as the first Danish monarch of the House of Glücksburg.
The beginning of his reign was marked by the Danish defeat in the Second Schleswig War and the subsequent loss of the duchies of Schleswig, Holstein and Lauenburg which made the king immensely unpopular. The following years of his reign were dominated by political disputes, for Denmark had only become a constitutional monarchy in 1849 and the balance of power between the sovereign and parliament was still in dispute. In spite of his initial unpopularity and the many years of political strife, in which the king was in conflict with large parts of the population, his popularity recovered towards the end of his reign, and he became a national icon due to the length of his reign and the high standards of personal morality with which he was identified.
Christian's six children with Louise married into other European royal families. Among his descendants are King Frederik X, King Philippe of Belgium, King Haakon VIII of Norway, Grand Duke Guillaume V of Luxembourg, King Charles III of the United Kingdom, and King Felipe VI of Spain.
Christian IX was born between 10 and 11 a.m. on 8 April 1818 at the residence of his maternal grandparents, Gottorf Castle, near the town of Schleswig in the Duchy of Schleswig, at the time a fief under the Crown of Denmark. Born as a prince of Schleswig-Holstein-Sonderburg-Beck, he was the fourth son of Friedrich Wilhelm, Duke of Schleswig-Holstein-Sonderburg-Beck, and Princess Louise Caroline of Hesse-Kassel. He was named after his mother's cousin Prince Christian Frederick of Denmark, the later King Christian VIII, who was also his godfather. Together with his wife, Caroline Amalie of Augustenborg, he had traveled from Augustenborg to Gottorp so that he could hold his godson at the christening, which was held at the end of May in the chapel of Gottorp Castle.
Prince Christian's father was the head of the ducal house of Schleswig-Holstein-Sonderburg-Beck, a junior male branch of the House of Oldenburg. The family descended from King Christian III of Denmark's younger son, John the Younger, Duke of Schleswig-Holstein-Sonderburg, whose grandson Duke August Philipp severed his ties with Denmark and emigrated to Germany where he acquired the manor of Haus Beck in Westphalia, after which the lineage was named Schleswig-Holstein-Sonderburg-Beck. His sons and their descendants went into Prussian, Polish and Russian service, until his great-great-grandson, Prince Christian's father, again went into Danish military service, where he was stationed in Holstein. It was there that he had met and married Prince Christian's mother, who was a daughter of Prince Charles of Hesse-Kassel, an originally German prince, who, however, had grown up at the Danish court and had married King Frederick V's youngest daughter, Princess Louise of Denmark. Prince Charles had made a career in Denmark, where he was a Danish field marshal and Royal Governor of the duchies of Schleswig and Holstein.
Through his father, Prince Christian was thus a direct male-line descendant of King Christian III of Denmark and an (albeit junior) agnatic descendant of Hedvig of Holstein (countess of Oldenburg), mother of King Christian I of Denmark, who was the "semi-Salic" heiress of her brother Adolf of Schauenburg, last Schauenburg duke of Schleswig and count of Holstein. As such, Prince Christian was eligible to succeed in the twin duchies of Schleswig-Holstein, but not first in line. Through his mother, he was thus a great-grandson of Frederick V, great-great-grandson of George II of Great Britain and a descendant of several other monarchs, but had no direct claim to any European throne.
Initially, the young prince grew up with his parents and many brothers and sisters at his maternal grandparents' residence at Gottorf Castle, the habitual seat of the royal governors of the duchies of Schleswig and Holstein. However, in 1824, the dowager duchess of Glücksburg, widow of Frederick Henry William, the last duke of the elder line of the house Schleswig-Holstein-Sønderborg-Glücksburg, who had himself died in 1779, died. Glücksburg Castle, located a little south of Flensburg Fjord, not far from city of Flensburg, was now empty, and on 6 July 1825, Duke Friedrich Wilhelm was appointed Duke of Glücksburg by his brother-in-law, King Frederick VI of Denmark. Duke Friedrich Wilhelm subsequently changed his title to Duke of Schleswig-Holstein-Sonderburg-Glücksburg and thus founded the younger Glücksburg line.
Subsequently, the family moved to Glücksburg Castle, where Prince Christian was raised with his siblings under their father's supervision. The Duke wrote to a friend: I raise my sons with rigor, that these may learn to obey, without, however, failing to make them available to the requirements and demands of the present. However, Duke Friedrich Wilhelm died of a cold that had developed into pneumonia at the age of just 46 on 17 February 1831 and, at the Duke's own discretion, scarlet fever, which had previously affected two of his children. His death left the duchess widowed with ten children and no money. Prince Christian was twelve years old when his father died.
Following the early death of his father, King Frederick VI, together with Prince William of Hesse-Philippstal-Barchfeld, a close friend of the Duke, became legal guardians of Prince Christian and his nine siblings. That same year, Prince Christian wanted to be educated as a naval officer, but during King Frederick VI's visit to Gottorp in 1831, shortly after Duke Wilhelm's funeral, the king agreed with his mother that Prince Christian would be sent to Copenhagen to receive an army officer training. Subsequently, in 1832, the year after his father's death, the 14-year-old Prince Christian moved to Copenhagen to be educated at the Land Cadet Academy, where he stayed at the house of Colonel Linde, the head of the Land Cadet Academy. He received private lessons at the academy and was rarely with the other cadets. On the other hand, the sonless royal couple took good care of the boy, as Queen Marie was his mother's sister and King Frederick VI his mother's cousin. Also, in 1838, Prince Christian's eldest brother, Duke Karl of Glücksborg, married the king and queen's youngest daughter, Princess Vilhelmine Marie, which further strengthened the bonds between them.
In 1835, Prince Christian was confirmed in the Garrison Church in Copenhagen. The following year, after completing his military education, he was appointed rittmeister at the Royal Horse Guards and was then housed in the Royal Horse Guards Barracks by Frederiksholms Kanal in central Copenhagen. There he lived under simple conditions until King Frederick VI in 1839 granted him a home in the Yellow Palace, an 18th-century town house at 18 Amaliegade, immediately adjacent to the Amalienborg Palace complex, the principal residence of the Danish royal family in the district of Frederiksstaden in central Copenhagen, where he came to live until 1865.