This double negative emphasizes that the Hivites were the only people who made peace with Israel. The phrase "one city" is a metonym for the people who lived in that one city. Alternate translation: "The only city that made peace with the army of Israel was the Hivites who lived in Gibeon" or "The only people who made peace with the army of Israel were the Hivites who lived in Gibeon" (See: [[rc://en/ta/man/jit/figs-doublenegatives]] and [[rc://en/ta/man/jit/figs-metonymy]])