Conversation so far:
What was this during?
During the War of 1812, the British captured the fort in the Siege of Fort Mackinac.
What did this do for him?
The victorious British attempted to protect their prize by building Fort George on the high ground behind Fort Mackinac.

Question: Why was this so terrible?
Self-contained rewrite: Why was building Fort George on the high ground behind Fort Mackinack so terrible