Nazis vs Play

Biog of Johan Huizinga. Noticed this in my researches on the book - Huizinga is the author of the classic work on play, Homo Ludens - and am somewhat rocked by the lines, "Finally, when his life was drawing to a close, and he was a prisoner of the Nazis, he collected his thoughts on this subject [play] into a book... From 1942 until his death in 1945 Johan Huizinga was held in detention by the Nazis." On second thoughts, what better book to write under National-Socialist confinement than a volume on play. Does anyone know more about Huizinga during this time?