Conversation so far:
When did he start fighting the Dutch?
Mount Merapi's eruption in 1822 and a cholera epidemic in 1824 furthered the view that a cataclysm is inbound.
Was he successful in his fight against the Dutch?
Many troops and leaders were defeated or deserted.

Question: Why did he fight the Dutch?
Self-contained rewrite: Why did Diponegoro fight the Dutch?