His uncle Prince Luitpold took power when a panel of physicians recommended his removal, and this man known as the "Mad King" drowned himself soon after.  
He entered the Seven Weeks' War on the side of Austria but, on his defeat, signed an alliance with Prussia.  As king he invited the exiled Richard Wagner to continue his musical work in Munich, during which time Wagner completed his Ring Cycle.  His uncle Prince Luitpold took power when a panel of physicians recommended his removal, and this man known as the "Mad King" drowned himself soon after.  FTP, name this King of Bavaria famous for his many castles like Neuschwanstein, the grandson of Ludwig I and cousin of Ludwig III.
He entered the Seven Weeks' War on the side of Austria but, on his defeat, signed an alliance with Prussia.  
Ludwig II or Louis II