The lack of institutional means to move the regular forces from a peacetime footing to war status reflected national policy and the decentralized nature of the federal government as much as it did failings within the armed forces. The nature of the naval service hindered institutional development. In peacetime the navy served largely overseas to represent American commercial interests, protect citizens and their property, and explore and chart unknown waters. The navy's wartime service was two-fold: to protect American coasts and attack enemy commercial shipping. Most of the trends noted in American military history in the early years of the republic also appear in the antebellum period. Serving mainly on the frontier, the army fostered national expansion through exploration, road building and river clearance, and fought Native Americans resisting the movement westward. Despite the evident flaws in the American military system, the United States won the Mexican War and prevailed again in 1865.