Strategic diversion possibly caught Rudolf in WWII (5)

I believe the answer is:

chess

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But I can't explain it at all! Could you help me understand?

(Other definitions for chess that I've seen before include "Ancient war game whose name may have derived for the Persian for 'king'" , "In which two bishops will participate" , "that has over thirty men on board" , "Game involving mates" , "Pieces moved in this" .)

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