The insurgents did everything they could to avoid the kind of conventional pitched battle that the French were expecting. They used the rugged terrain to their advantage, launching surprise attacks and then disappearing into the mountainous interior. This not only negated any tactical or technological superiority the colonial army had; it also bought the rebels time until the yellow fever season arrived.[78] It proved to be a wildly effective strategy. When the rains came, the French fell sick in terrifying numbers.
