Historically, that's typically what happened. If the aggressor was beaten back, the defender could decide to push them a little extra back and grab some land or a "buffer zone". Some years later, the aggressor is mad that they lost land, and have constructed a story about how they were the victims (after all, they're the ones that ended up losing land). Of course, they need to "retake their stolen land", so you get a new war. Rinse and repeat every couple decades, and you have European history up until about 1945.