As Emperor Wilhelm's heir, he was the last Crown Prince of the German Empire and the Kingdom of Prussia, until the abolition of the monarchy. Wilhelm became crown prince at the age of six in 1888, when his grandfather Frederick III died and his father became emperor.
Following a long battle with throat cancer, Emperor Frederick III died on June 15, 1888. Wilhelm II succeeded his father, becoming kaiser of Germany at the tender age of 29. Kaiser of Germany...
Wilhelm III, ( German: Friedrich Wilhelm Victor August Ernst von Preußen; Frederick William Victor August Ernest of Prussia; 6 May 1882 – 20 July 1951) was German Emperor and King of Prussia from June 4, 1941 at during World War II until his death on July 20, 1951.
Mary II died of smallpox on 28 December 1694, leaving William III to rule alone. William deeply mourned his wife's death.  Despite his conversion to Anglicanism , William's popularity in England plummeted during his reign as a sole monarch.
William III, (born November 14 [November 4, Old Style], 1650, The Hague, Netherlands—died March 19 [March 8], 1702, London, England), stadholder of the United Provinces of the Netherlands as William III (1672–1702) and king of England, Scotland, and Ireland (1689–1702), reigning jointly with Queen Mary II (until her death in 1694).
Kaiser Wilhelm I died in Berlin on 9 March 1888, and Prince Wilhelm's father ascended the throne as Frederick III. He was already experiencing an incurable throat cancer and spent all 99 days of his reign fighting the disease before dying. On 15 June of that same year, his 29-year-old son succeeded him as German Emperor and King of Prussia.
Upon Wilhelm's death at the age of ninety on 9 March 1888, the thrones passed to Frederick, who had 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, aged fifty-six, following unsuccessful medical treatments for his condition.
In late 1918, he was forced to abdicate. He spent the rest of his life in exile in the Netherlands, where he died at age 82. Kaiser Wilhelm II’s Early Years
Died: 8 March 1702 at Kensington Palace, London Parents: William II, Prince of Orange, and Mary, Princess Royal of Britain Mary II: key dates and facts Born: 30 April 1662 at St James’s Palace, London Died: 28 December 1694 at Kensington Palace Parents: King James VII and II and Anne Hyde
William III and Mary II were crowned as joint monarchs in the Abbey on 11th April 1689 – the first time this had happened in England. He used the ancient Coronation Chair during the ceremony and another chair was specially made for Mary to sit in. There were no children, the throne passing to Mary's sister Anne.