Federalists were supporters of the proposed U.S. Constitution during the late 18th century who advocated for a strong national government and a system of checks and balances. They believed that a centralized authority was essential to maintain order and protect individual liberties, standing in contrast to the Anti-Federalists, who feared that a strong central government would infringe on states' rights and individual freedoms. Federalists played a critical role in the ratification process of the Constitution, emphasizing the need for a robust federal structure to address the challenges facing the nation at that time.