Question: The Army Group German Crown Prince was a group that was under the command of the eldest child of which future German emperor?

Context paragraphs:
Emperor Jianwen of Liang: Emperor Jianwen of Liang (梁簡文帝) (2 December 503 – 551), personal name Xiao Gang (蕭綱), courtesy name Shizuan (世纘), nickname Liutong (六通), was an emperor of the Chinese Liang Dynasty.  He was initially not the crown prince of his father Emperor Wu, the founder of the dynasty, but became the crown prince in 531 after his older brother Xiao Tong died.  In 549, the rebellious general Hou Jing captured the capital Jiankang, and Hou subsequently held both Emperor Wu and Crown Prince Gang under his power, having Crown Prince Gang take the throne (as Emperor Jianwen) after Emperor Wu's death later that year.  During Emperor Jianwen's reign, he was almost completely under Hou's control, and in 551, Hou, planning to take the throne himself, first forced Emperor Jianwen to yield the throne to his grandnephew Xiao Dong the Prince of Yuzhang, and then sent messengers to suffocate the former emperor.

Wilhelm, German Crown Prince: Wilhelm, German Crown Prince (German: "Kronprinz Wilhelm von Preußen" ; 6 May 1882 – 20 July 1951) , full name Friedrich Wilhelm Victor August Ernst, was the eldest child of the future German Emperor Wilhelm II and his wife Empress Augusta Victoria, and the last Crown Prince of the German Empire and the Kingdom of Prussia.  After the death of his grandfather Emperor Frederick III, Wilhelm became crown prince at the age of six, retaining that title for more than 30 years until the fall of the empire on 5 November 1918.  During World War I, he commanded the 5th Army from 1914 to 1916 and was commander of Army Group German Crown Prince for the remainder of the war.  Crown Prince Wilhelm became Head of the House of Hohenzollern on 4 June 1941 following the death of his father and held the position until his own death on 20 July 1951.

Duchess Cecilie of Mecklenburg-Schwerin: Duchess Cecilie of Mecklenburg-Schwerin (Cecilie Auguste Marie; 20 September 1886 – 6 May 1954) was the last German Crown Princess and Crown Princess of Prussia as the wife of German Crown Prince Wilhelm, the son of German Emperor Wilhelm II.

Victoria, Princess Royal: Victoria, Princess Royal (Victoria Adelaide Mary Louisa; 21 November 1840 – 5 August 1901) was German Empress and Queen of Prussia by marriage to German Emperor Frederick III.  She was the eldest child of Queen Victoria of the United Kingdom and Prince Albert, and was created Princess Royal in 1841.  She was the mother of Wilhelm II, German Emperor.

Army Group Rupprecht of Bavaria: The Army Group Rupprecht of Bavaria or Army Group A (German: "Heeresgruppe Kronprinz Rupprecht von Bayern") was an Army Group of the German Army, which operated on the Western Front under command of Rupprecht, Crown Prince of Bavaria , between 28 August 1916 and 11 November 1918 during World War I.  It was formed from the short-lived Army Group Gallwitz under Max von Gallwitz (19 July - 28 August 1916).

Frederick III, German Emperor: Frederick III (German: "Friedrich" ; 18 October 1831 – 15 June 1888) was German Emperor and King of Prussia for ninety-nine days in 1888, the Year of the Three Emperors.  Friedrich Wilhelm Nikolaus Karl, known informally as "Fritz", was the only son of Emperor Wilhelm I and was raised in his family's tradition of military service.  Although celebrated as a young man for his leadership and successes during the Second Schleswig, Austro-Prussian and Franco-Prussian wars, he nevertheless professed a hatred of warfare and was praised by friends and enemies alike for his humane conduct.  Following the unification of Germany in 1871 his father, then King of Prussia, became the German Emperor.  Upon Wilhelm's death at the age of ninety on 9 March 1888, the thrones passed to Frederick, who had by then been German Crown Prince for seventeen years and Crown Prince of Prussia for twenty-seven years.  Frederick was suffering from cancer of the larynx when he died on 15 June 1888, aged fifty-six, following unsuccessful medical treatments for his condition.

Liu Ju: Liu Ju (Traditional Chinese: 劉據) (128 BC – 91 BC), formally known as Crown Prince Wei (衛太子) and posthumously as Crown Prince Li (戾太子, literally "the Unrepentant Crown Prince") was a Western Han Dynasty crown prince.  He was the eldest son and the heir apparent to his father, Emperor Wu of Han, until his death at age 38 during the political turmoil in 91 BC.  Contrary to his less-than-flattering posthumous name, Liu Ju was generally regarded by historians as a well-mannered, benevolent, morally upright man who, by circumstances out of his control, was forced into an uprising against his father's army and died as a consequence of the rebellion.

Army Group German Crown Prince: The Army Group German Crown Prince or Army Group B (German: "Heeresgruppe Deutscher Kronprinz") was an Army Group of the German Army, which operated on the Western Front under command of Wilhelm, German Crown Prince, between 1 August 1915 and 11 November 1918 during World War I.

Princess Alexandrine of Prussia (1915–1980): Princess Alexandrine Irene of Prussia (7 April 1915 – 2 October 1980) was the eldest daughter and fifth child of Wilhelm, German Crown Prince, and Cecile of Mecklenburg-Schwerin.  Her grandparents were Wilhelm II, German Emperor and his wife Augusta Victoria of Schleswig-Holstein, and Frederick Francis III of Mecklenburg-Schwerin and Grand Duchess Anastasia Mikhailovna of Russia.  Alexandrine was a member of the House of Hohenzollern.

Princess Charlotte of Prussia: Princess Charlotte of Prussia (Viktoria Elisabeth Auguste Charlotte; 24 July 1860 – 1 October 1919) was Duchess Consort of Saxe-Meiningen as the wife of Bernhard III, the duchy's last ruler.  Born at the "Neues Palais" in Potsdam, she was the second child and eldest daughter of Prince Frederick of Prussia, a member of the House of Hohenzollern who became Crown Prince of Prussia in 1861 and German Emperor in 1888.  Through her mother Victoria, Princess Royal, Charlotte was the eldest granddaughter of the British monarch Queen Victoria and her consort Prince Albert of Saxe-Coburg and Gotha.

Supporting paragraphs: Army Group German Crown Prince Wilhelm, German Crown Prince
Answer: Wilhelm II