Question: In what War did the father of Princess Christina Margarethe of Hesse die?

Context paragraphs:
Christina Ingesdotter of Sweden: Princess Christina Ingesdotter of Sweden (Swedish: "Kristina Ingesdotter") (11th century – 18 January 1122) was a Swedish princess and a princess consort of Veliky Novgorod, Rostov and Belgorod, by marriage to Grand Prince Mstislav I of Kiev.

Margarita of Diez: Margarita of Diez (German - "Margarethe von Diez"; 14 October 1544 - 12 July 1608) was a German noblewoman.  Born in Spangenberg, she was the fourth child and eldest daughter of Philip I, Landgrave of Hesse and his second morganatic wife Margarethe von der Saale, whom he had married whilst still married to his first wife Christine of Saxony, with whom he had already had five sons and five daughters.

Princess Christina, Mrs. Magnuson: Princess Christina, Mrs. Magnuson, {'1': ", '2': ", '3': 'LoK av KMO', '4': "} ("Christina Louise Helena", born 3 August 1943) is the youngest of four older sisters of King Carl XVI Gustaf of Sweden.  She generally uses the name Christina Magnuson.

Princess Christina Margarethe of Hesse: Princess Christina Margarethe of Hesse (German: "Prinzessin Christina Margarethe von Hessen" ; 10 January 1933 – 22 November 2011) was the eldest daughter of Prince Christoph of Hesse and Princess Sophie of Greece and Denmark.  From 1956 to 1962, she was married to Prince Andrew of Yugoslavia, with whom she had two children.  Her second marriage to Robert Floris van Eyck, a Dutch artist based in London, lasted from 1962 to 1986.

Princess Irene of Hesse and by Rhine: Princess Irene of Hesse and by Rhine ("Irene Luise Marie Anne, Princess of Hesse and by Rhine", 11 July 1866 – 11 November 1953) was the third child and third daughter of Princess Alice of the United Kingdom and Louis IV, Grand Duke of Hesse and by Rhine.  Her maternal grandparents were Queen Victoria and Prince Albert of Saxe-Coburg and Gotha.  Her paternal grandparents were Prince Charles of Hesse and by Rhine and Princess Elizabeth of Prussia.  She was the wife of Prince Henry of Prussia, a younger brother of Wilhelm II, German Emperor and her first cousin.  The SS "Prinzessin Irene", a liner of the North German Lloyd was named after her.

Princess Christina of the Netherlands: Princess Christina of the Netherlands (Maria Christina; born 18 February 1947) is the youngest of four daughters born to Queen Juliana of the Netherlands and Prince Bernhard of Lippe-Biesterfeld.

Prince Christoph of Hesse: Christoph Ernst August of Hesse (Frankfurt, 14 May 1901 – Apennine Mountains near Forlì, 7 October 1943) was the fifth son of Prince Frederick Charles of Hesse and Princess Margaret of Prussia.  He was a German SS officer killed accidentally during World War II.

Line of succession to the former Hessian throne: The Electorate of Hesse was abolished in 1866 when it was annexed by the Kingdom of Prussia, while the Grand Duchy of Hesse and by Rhine came to an end in 1918.  Like most former German realms of the Holy Roman Empire the succession in Hessian lands was semi-Salic, with the nearest female kinswoman of the last male inheriting the crown upon extinction of the dynasty in the male line.  The current pretender to both Hessian thrones is Donatus, Landgrave of Hesse, from the electoral line of the family, which inherited its claim to the grand duchy following the death of Prince Louis of Hesse and by Rhine in 1968.  Donatus became head of the House of Hesse on the death of his father, Prince Moritz, in 2013.  Landgrave Donatus is the titular Grand Duke and Elector of Hesse.

Hesse: Hesse ( or ) or Hessia (German: "Hessen" ] , Hessian dialect: "Hesse" ] ) is a federal state ("Land") of the Federal Republic of Germany, with just over six million inhabitants.  The state capital is Wiesbaden; the largest city is Frankfurt am Main.  Until the unification of Germany, the territory of Hesse was occupied by the Grand Duchy of Hesse, the Duchy of Nassau, the free city of Frankfurt and the Electorate of Hesse, known also as Hesse-Cassel.  Due to divisions after World War II, the modern federal state does not cover the entire cultural region of Hesse, which includes both the State of Hesse and the area known as Rhenish Hesse (Rheinhessen) in the neighbouring state of Rhineland-Palatinate.

Mafalda von Hessen: Mafalda Margarethe Prinzessin von Hessen (born 6 July 1965), known also as Princess Mafalda of Hesse, is a German aristocrat and fashion designer.  She is the eldest child of Moritz, Landgrave of Hesse and Princess Tatiana of Sayn-Wittgenstein-Berleburg.

Supporting paragraphs: Princess Christina Margarethe of Hesse Prince Christoph of Hesse
Answer: World War II