Arthur Gerald Wellesley, Earl of Mornington, is the great-great-grandson of what  last German Emperor ("Kaiser") and King of Prussia?
Arthur Wellesley, Earl of Mornington Arthur Gerald Wellesley, Earl of Mornington (born 31 January 1978 at St Mary's Hospital in Paddington, London) is the son of Charles Wellesley, 9th Duke of Wellington. The Wellesleys are an aristocratic Anglo-Irish family. Through his mother, Antonia von Preussen, Duchess of Wellington, he is great-great-grandson of Kaiser Wilhelm II. As a descendant of Queen Victoria, he is eligible to succeed to the British throne.
Prince Leopold of Bavaria Leopold Maximilian Joseph Maria Arnulf, Prinz von Bayern (9 February 1846 – 28 September 1930) was born in Munich, the son of Prince Regent Luitpold of Bavaria (1821–1912) and his wife Archduchess Augusta of Austria (1825–1864). He was a Field Marshal ("Generalfeldmarschall") who commanded German and Austro-Hungarian forces on the Eastern Front in World War I.