The future Christian IX of Demark was born on 8 April 1818, the fourth son of Friedrich Wilhelm, Duke of Schleswig-Holstein-Sonderburg-Beck and Princess Louise Caroline of Hesse.
Although he was really in line for any throne, the newborn was related six ways to Sunday to the crowned heads of Europe. Among other connections, his father was the head of the junior male branch of the House of Oldenburg, and thus a direct (albeit too distant to have hopes of being named to the succession) male-line descendant of King Christian III of Denmark. The baby’s paternal grandmother was also decended from Helvig of Schauenburg, the mother of King Christian I of Denmark. The infant’s mother was maternal granddaughter of Frederick V of Denmark and therefore the great-granddaughter of George II of Great Britain.
Such a well-connect baby had a very prestigious godfather, Prince Christian of Denmark (the later King Christian VIII) whom he was named after.
Christian was educated for a role in the military, but his main duty was to schmooze with other bigwigs, marry well, and produce more little Schleswig-Holstein-Sonderburg-Glücksburgs. He wooed his third cousin, Queen Victoria, but he lost out to another one of his cousins, Prince Albert of Saxe-Coburg and Gotha. Christian then married a different cousin, Princess Louise of Hesse-Kassel (or Hesse-Cassel), one of his godfather Christian VIII’s nieces, in the spring of 1842.
The marriage between Christian and Louise was masterminded by King Christian VIII. For more than a decade there had been much ado about which of the descendants of the the king’s childless son, future King Frederick VII of Denmark, and his equally childless uncle, Prince Ferdinand, would eventually inherit the Danish throne. King Christian VIII favored his godson, in part because he was fond of him and also because:
Prince Christian had been a foster “grandson” of the “grandchildless” royal couple Frederick VI and his Queen consort Marie (Marie Sophie Friederike of Hesse). Familiar with the royal court and the traditions of the recent monarchs, their young ward Prince Christian was great-nephew of Queen Marie and descendant of a first cousin of Frederick VI. He was brought up as Danish, having lived in Danish-speaking lands of the royal dynasty and had not become a German nationalist, which made him a relatively good candidate from the Danish point of view. As junior agnatic descendant, he was eligible to inherit Schleswig-Holstein, but was not the first in line. As a descendant of Frederick III, he was eligible to succeed in Denmark, although here too, he was not first-in-line.
King Christian of Denmark’s closest female relative was Princess Charlotte of Denmark, Christian’s mother-in-law. Louise’s mother and brother, and elder sister too, were subsequently pressured to renounced their rights to the throne in favor of Princess Louise. Louise then renounced her rights to the throne in favor of her husband. Although Christian VIII’s heir didn’t particularly like Prince Christian or Louise, by the time his father died in 1848 the backstairs deals had been in effect long enough to be practically impossible to undo without a horrible fuss and perhaps international warfare. Thus, “the decision was implemented by the Danish Law of Succession of 31 July 1853—more precisely, the Royal Ordinance settling the Succession to the Crown on Prince Christian of Glücksburg —which designated him as heir to the entire Danish monarchy following the extinction of the male line of Frederick III and granted him the title Prince of Denmark.”
After Fredrick VII’s death, King Christian IX ruled Demark from 1863 until his own passing 1906. For the first year of his reign he was also the Duke of Schleswig, Holstein and Lauenburg, but the Danish defeat in the Second Schleswig War lost king and country those duchies to Austria and Prussia, who then fought for the lands between themselves. This loss
“made the king immensely unpopular. The following years of his reign were dominated by political disputes as 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, where 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.”
King Christian IX’s main claim to fame was through his six children, who intermarried among royalty throughout Europe and Great Britain.
Several of his grandsons became kings, including Nicholas II of Russia, Constantine I of Greece, George V of the United Kingdom, Christian X of Denmark and Haakon VII of Norway. Today, Queen Margrethe II of Denmark, Queen Elizabeth II of the United Kingdom, King Philippe of Belgium, King Harald V of Norway, King Felipe VI of Spain, both King Michael I of Romania and his wife Queen Anne of Romania, as well as the Grand Duke Henri of Luxembourg are all Christian IX’s descendants. Moreover, royal consort such as Prince Philip, Duke of Edinburgh (through Christian’s grandson Prince Andrew of Greece and Denmark) and former consort Queen Sofía of Spain are his agnatic descendants. Finally, Constantine II, the last “King of the Hellenes”, and his consort the former Queen Anne-Marie (the paternal uncle and aunt of Prince Philip, Duke of Edinburg) were the grandson and great-granddaughter of Christian IX.
All this royal intermarriage makes it clear why no one turned a hair when Fanny Price married her first cousin Edmund Bertram in Mansfield Park! Marriages between first cousins didn’t really fall out of vogue until after Charles Darwin made everyone think more seriously about the potentially negative consequences of interbreeding.