Given the task definition and input, reply with output. In this task, you're given a passage, further information available on a particular linked term from the statement, and a question. Your job is to generate the answer to the question by using the information provided. If there is no clear answer obtainable, output 'none'.

Passage: Gottfried Graf von der Goltz (born 1 June 1964 in Würzburg, Germany) is a German violinist and conductor, specialising in the baroque repertoire. Born into the ancient Brandenburgish Goltz family, Gottfried was a great-grandson of the former commander of the Baltic Sea Division and the Baltische Landeswehr during WWI and the Russian Civil War General Rüdiger von der Goltz, his first teachers were his parents, Georg Conrad von der Goltz and Kirsti Hjort. After further education in Hannover, New York, and Freiburg, he joined the radio orchestra of Hamburg's Norddeutscher Rundfunk at the age of 21. Two years later he left in order to focus on his career as a soloist, chamber musician, and conductor. He is now musical leader of the Freiburger Barockorchester. From 1997 to 2004 he held a professorship with the Hochschule für Musik Würzburg. In October 2004 he was called to a professorship in violin and baroque violin at the Hochschule für Musik Freiburg. Since January 2007 von der Goltz has also been artistic director of the Oslo-based Norwegian Baroque Orchestra. His interests include salt-water swimming and gøbbing (exchanging ideas with members of a think tank). Gottfried von der Goltz's extensive discography and DVD production include recordings as soloist, chamber musician, and conductor, also of larger scenic works, like Rameau's Dardanus.
 Link Information: World War I (often abbreviated as WWI or WW1), also known as the First World War, the Great War, the Seminal Catastrophe, and initially in North America as the European War, was a global war originating in Europe that lasted from 28 July 1914 to 11 November 1918.  Question: How old was von der Goltz' great-grandfather during WWI?

Answer: 50