On the subject of Kaiser Wilhelm during World War 2. There was a interesting, albeit brief (5 min) segment in this morning's: BBC Sounds - Broadcasting House - 28/10/2018 "Sunday morning magazine programme. Presented by Paddy O'Connell." It starts just prior to the 40 min mark with some background, including WW1 etc. and continues to his death under Nazi occupation etc. during WW2. Life in exile: Wilhelm II, German Emperor - Wikipedia
Thank you for starting this thread. Stefan NB: I lived in Hannover from 1948 til 1966 and Ernst August from the Hannover line is very well known to most locals.