Louis XIV, along with his chief advisor, Louvois; his foreign minister, Colbert de Croissy; and his technical expert, Vauban, developed France's defensive strategy. Vauban had advocated a system of impregnable fortresses along the frontier to keep France's enemies out. To construct a proper system, however, the King needed to acquire more land from his neighbours to form a solid forward line. That rationalisation of the frontier would make it far more defensible and define it more clearly in a political sense, but it also created the paradox that Louis's ultimate goals were defensive, but he pursued them by hostile means. He grabbed the necessary territory in the Reunions, a strategy that combined legalism, arrogance and aggression.