What do architecture and war have in common?

This article, in many ways, shows the evolution of both machines and structures in regard to each other. As machines got bigger, so did castle walls. As castle walls got bigger, machines got bigger. Thus, the competitiveness between enemies resulted in increased technological efforts and approaches to innovation. The structures of castles grew to include both inner and outer walls, along with larger ramparts and thicker tower fortifications. This relates directly towards structures because it demonstrates one way in which structures evolve. When I think of the evolution of structures, I would normally approach it from a more artistic approach. I would think of the evolution from gothic architecture to modern architecture (from the cathedrals of Spain to Frank Lloyd Wright’s “Falling Water”). I would even think of more avant-garde architecture such as Gaudi’s “Casa Batllo”. It never occurred to me that evolution of structures would also be influenced by the threat of enemies and competition.