What personality are you doing? I'm doing Hatshepsut so obviously my answer would include things on how she promoted herself as a warrior pharaoh to maintain power that she strictly speaking shouldn't have had, while not actually being a warrior pharaoh, wheras if you were doing Akenaten like jimmik your answer would be totally different. I'm going to assume from the open nature of the question they expect several examples of different Pharaohs and how they used the military image.
Anyway... make sure you mention the kicking out of the Hyksos invaders because that's basically the main point relating the 18th to military exploits, also talk about Thutmose 1 and his military conquests etc, then link these to the image promoted in sources.
Basically I think you need to talk about how the military image promoted by various examples of Pharaohs in the 18th dynasty helped them to govern egypt, maintain power, increase the overall wealth etc of Egypt. I could be wrong but that's my interpretation.