In 1787, at the Constitutional Convention, the new Constitution had to be ratified by nine of the thirteen states. Any states that did not ratify the Constitution would not be a part of the United States. Many people opposed the creation of a national government that would have power over the state governments. They were called Anti-Federalists. They believed each state should be a sovereign country. The Federalists wanted a strong central government. In order to pass the Constitution and begin a new form of government a compromise was reached. Leading Federalists such as Patrick Henry and George Mason suggesting adding a Bill of Rights to the Constitution in the form of amendments. On September 25, 1789, Congress approved twelve articles of amendment to the Constitution and submitted them to the states for ratification. On December 15, 1791, the states ratified ten of the amendments which became the Bill of Rights.