King Christian IX of Denmark (8 April 181829 January 1906), known as the "father-in-law of Europe", ruled Denmark from 1863 to 1906. He and his queen consort, Louise of Hesse-Kassel (7 September 181729 September 1898), became the ancestors of many members of European royalty.

In 1842, prior to becoming King of Denmark, Christian married Louise, whose familial connections allowed him to secure his status as the heir-presumptive to the Danish throne in 1852. Christian and Louise had three sons and three daughters together, and the couple actively involved themselves in their children's education because of their limited finances. Although Christian had an affectionate relationship with his daughters, he rejected his eldest son, Frederick, over political differences.

After the commencement of Christian's reign as King of Denmark, his popularity gradually improved among his subjects, partially because of Louise's efforts to marry their children with members of royal families across Europe, including their daughter Princess Alexandra with Albert Edward, Prince of Wales (later Edward VII), and their daughter Princess Dagmar with Alexander, Tsarevich of Russia (later Alexander III).

All of Christian and Louise's six children would go on to have progeny of their own. In addition, some of Christian and Louise's extended descendants would rule as monarchs themselves in European countries. For example, Christian and Louise's grandsons Constantine I, Nicholas II, and George V reigned over Greece, Russia, and the United Kingdom, respectively.

Background King Christian IX For the first 13 years of his life, Christian lived in Germany. Following the death of his father, Friedrich Wilhelm, in 1831, Christian trained as an officer in Copenhagen. He fought on behalf of the Danish Unitary State in the First Schleswig War.

In 1852, Christian became the heir presumptive to the Danish throne. Following the death of his second cousin King Frederick VII 11 years later, Christian became King of Denmark. Due to Christian's German background, he was unpopular among his subjects during the start of his reign. He nearly abdicated in 1864 after Denmark's loss in the Second Schleswig War. Christian's popularity recovered, however, as his children married into several European royal families.

Queen Louise Born Princess Louise of Hesse-Kassel, Louise became Queen of Denmark in 1863. Because her mother was a sister of King Christian VIII, Louise's marriage to Christian IX was an important factor in his rise to the Danish throne. Moreover, Louise was instrumental in marrying her children across European royalty, which helped increase her husband's popularity among the Danish people.

As Queen of Denmark, Louise exemplified the female ideas of her time. Despite remaining in the shadow of Christian, she showed artistic and social talent. Through her charity work, Louise founded the Diakonissestiftelsen in Copenhagen.

Marriage Christian and Louise were married in 1842.

+ Family of Christian IX, King of DenmarkPortraitDescendants Christian IX, King of Denmark 8 April 181829 January 19066 children, including: Frederick VIII, King of Denmark Alexandra, Queen of the United Kingdom George I, King of the Hellenes Maria Feodorovna, Empress of Russia Princess Louise of Hesse-Kassel7 September 181729 September 1898

Children King Christian IX, together with Queen Louise, had six children: Frederick, Alexandra, George, Dagmar, Thyra, and Valdemar. Because of the strained finances and limited fortunes that Christian and Louise had before 1852, they were actively involved in the education of Dagmar and her siblings during that time. Later, from 1875 to 1900, Christian and Louise would annually welcome their children and grandchildren across six different European royal houses at Fredensborg Palace in Denmark.

Within Christian and Louise's family, Thyra was called the "gentle and good daughter" by her father. In addition, Alexandra and Dagmar were respectively seen as the "pretty" and "clever" girls. In contrast, Christian rejected Frederick, then Crown Prince of Denmark, because of their contrasting conservative and reformist mindsets, respectively. Furthermore, Christian had reservations about George becoming King of the Hellenes after the Greek National Assembly elected the latter to be their monarch, seeing the country's throne as a doubtful proposition. Nevertheless, George successfully persuaded his father and assumed the Greek throne in 1863. This influenced Valdemar's decision to decline an offer for the Bulgarian throne in 1878. He did not want to risk going to war with his brother George, given the relations between Bulgaria and Greece at the time.

+ Children of Christian IX, King of Denmark Frederick VIII, King of Denmark Married 1869, Princess Louise of Sweden (1851–1926) 8 children (including Christian X, King of Denmark, and Haakon VII, King of Norway) Princess Alexandra of Denmark Married 1863, Edward VII, King of the United Kingdom (1841–1910; ) 6 children (including George V, King of the United Kingdom, and Maud, Queen of Norway) George I, King of the Hellenes Married 1867, Grand Duchess Olga Constantinovna of Russia (1851–1926) 8 children (including Constantine I, King of the Hellenes) Princess Dagmar of Denmark Married 1866, Alexander III, Emperor of Russia (1845–1894; ) 6 children (including Nicholas II, Emperor of Russia) Princess Thyra of Denmark Married 1878, Ernest Augustus, Crown Prince of Hanover (1845–1923) 6 children (including Alexandra, Grand Duchess of Mecklenburg-Schwerin, and Ernest Augustus, Duke of Brunswick) Prince Valdemar of Denmark Married 1885, Princess Marie of Orléans (1865–1909) 5 children

Grandchildren Christian IX and Louise had 38 grandchildren: eight children of Frederick VIII, six children of Alexandra, seven children of George I, six children of Dagmar, six children of Thyra, and five children of Valdemar.

Children of Frederick VIII and Louise

At the age of 17, Princess Louise of Sweden became engaged to King Frederick VIII of Denmark, then called Frederick, Crown Prince of Denmark, at Bäckaskog Castle in Sweden. Frederick and Louise would later marry in 1869 in Stockholm. This marriage took place in the context of a desire for a Scandinavian union in both Denmark and Sweden.

Together, Frederick and Louise had eight children. Two of these children, Christian and Haakon, became King of Denmark and King of Norway, respectively. Frederick and Louise's family came to be defined by Louise's piety. Moreover, Louise oversaw the strictly disciplined education of her children.

Over time, Frederick and Louise's marriage became a reasonably happy one. However, because of Frederick's estrangement from his father, he and his wife kept their distance from his relatives. In addition, Louise had difficult relationships with her in-laws in the Danish royal family.

+ Children of Frederick VIII, King of Denmark Portrait Christian X, King of Denmark Married 1898, Duchess Alexandrine of Mecklenburg-Schwerin (1879–1952) and had 2 children: Frederik IX, King of Denmark (1899–1972; ) Father of Margrethe II, Queen of Denmark, and Anne-Marie, Queen of the Hellenes Knud, Hereditary Prince of Denmark (1900–1976) Haakon VII, King of Norway Married 1896, Princess Maud of Wales (1869–1938) and had 1 child: Olav V, King of Norway (1903–1991; ) Father of Harald V, King of Norway Princess Louise of Denmark Married 1896, Prince Frederick of Schaumburg-Lippe (1868–1945) and had 3 children: Princess Marie Louise of Schaumburg-Lippe (1897–1938) Prince Christian of Schaumburg-Lippe (1898–1974) Princess Stephanie of Schaumburg-Lippe (1899–1925) Prince Harald of Denmark Married 1909, Princess Helena Adelaide of Schleswig-Holstein-Sonderburg-Glücksburg (1888–1962) and had 5 children: Princess Feodora of Denmark (1910–1975) Princess Caroline-Mathilde of Denmark (1912–1995) Princess Alexandrine-Louise of Denmark (1914–1962) Prince Gorm of Denmark (1919–1992) Prince Oluf of Denmark (1923–1990) Princess Ingeborg of Denmark Married 1897, Prince Carl, Duke of Västergötland (1861–1951) and had 4 children: Princess Margaretha of Sweden (1899–1977) Märtha, Crown Princess of Norway (1901–1954) Mother of Harald V, King of Norway Astrid, Queen of the Belgians (1905–1935) Mother of Joséphine-Charlotte, Grand Duchess of Luxembourg, Baudouin, King of the Belgians, and Albert II, King of the Belgians Prince Carl, Duke of Östergötland (1911–2003) Princess Thyra of Denmark Died unmarried Prince Gustav of Denmark Died unmarried Princess Dagmar of Denmark Married 1922, Jørgen Castenskjold (1893–1978) and had 4 children, including

Christian Ludwig Castenskjold (1926–2024) Jørgen Castenskjold (1929–1964)

Children of Alexandra and Edward VII

In 1861, Princess Alexandra met King Edward VII of the United Kingdom, then called Albert Edward Prince of Wales, at the Speyer Cathedral in Germany. Edward was the eldest son of Queen Victoria and Prince Albert. Edward later proposed to Alexandra in 1862, and they married in 1863 at St George's Chapel in Windsor Castle in the United Kingdom.

Although Alexandra and Edward got along fairly well, Edward engaged in several affairs during their marriage. However, for the most part, Alexandra did not pay attention to her husband's romantic liaisons.

Together, Alexandra and Edward had six children. One of these children, Alexander John, died in infancy. Furthermore, Alexandra and Edward's eldest son, Albert Victor, died in 1892 after contracting an illness during a flu pandemic. Albert Victor's death devastated Alexandra.

The three daughters of Edward and Alexandra, Louise, Victoria, and Maud, were known for being active during their youth. As the daughters aged, they became more withdrawn. Alexandra did not want Louise, Victoria, and Maud to marry because her daughters had two brothers who could potentially follow Edward to the British throne. However, both Louise and Maud eventually married.

Portrait of Queen Alexandra and King Edward VII's family

+ Children of Alexandra, Queen of the United Kingdom Portrait Prince Albert Victor, Duke of Clarence and Avondale Died unmarried George V, King of the United Kingdom Married 1893, Princess Victoria Mary of Teck (1867–1953) and had 6 children: Edward VIII, King of the United Kingdom (1894–1972; ) George VI, King of the United Kingdom (1895–1952; ) Father of Elizabeth II, Queen of the United Kingdom Mary, Princess Royal (1897–1965) Prince Henry, Duke of Gloucester (1900–1974) Prince George, Duke of Kent (1902–1942) Prince John of the United Kingdom (1905–1919) Louise, Princess Royal Married 1889, Alexander Duff, 1st Duke of Fife (1849–1912), and had 3 children: Alistair Duff, Marquess of Macduff (1890–1890) Princess Alexandra, 2nd Duchess of Fife (1891–1959) Princess Maud of the United Kingdom (1893–1945) Princess Victoria of the United Kingdom Died unmarried Princess Maud of Wales Married 1896, Haakon VII, King of Norway (1872–1957; ), and had 1 child: Olav V, King of Norway (1903–1991; ) Father of Harald V, King of Norway Prince Alexander John of Wales

Children of George I and Olga

In 1863, the Kingdom of Greece was without a monarch. The royal houses of Europe believed that George I, then Prince William of Denmark, would be a suitable candidate for the Greek throne. Consequently, George traveled to Greece, a country that he had never visited before, that same year to start his reign.

After arriving in Greece, George married Grand Duchess Olga Constantinovna of Russia in 1867. George and Olga had eight children together.

+ Children of George I, King of the Hellenes Portrait Constantine I, King of the Hellenes Married 1889, Princess Sophia of Prussia (1870–1932) and had 6 children: George II, King of the Hellenes (1890–1947; ) Alexander, King of the Hellenes (1893–1920; ) Father of Alexandra, Queen of Yugoslavia Helen, Queen Mother of Romania (1896–1982) Mother of Michael I, King of Romania Paul, King of the Hellenes (1901–1964; )