During the First World War, campaigns were frozen into inaction, mired in a trench warfare stalemate that lasted years. During the Second World War, the lessons of the last war were not learned as France built a supposedly "impregnable" Maginot Line. In 1940, the static Maginot fortifications were easily outflanked by Nazi Germany's rapid mechanized legions. With scientists and military tacticians working together, weapons of war have now become more effective and proved the value of "the battle of brains".