The Articles of Confederation and Perpetual Union was an agreement among the 13 states of the United States of America, formerly the Thirteen Colonies, that served as the nation's first frame of government. It was approved after much debate (between July 1776 and November 1777) by the Second Continental Congress on November 15, 1777, and sent to the states for ratification. The Articles of Confederation came into force on March 1, 1781, after ratification by all the states. A guiding principle of the Articles was to establish and preserve the independence and sovereignty of the states. The weak central government established by the Articles received only those powers which the former colonies had recognized as belonging to king and parliament. The document provided clearly written rules for how the states' league of friendship, known as the Perpetual Union, would be organized. During the ratification process, the Congress looked to the Articles for guidance as it conducted business, directing the war effort, conducting diplomacy with foreign states, addressing territorial issues and dealing with Native American relations. Little changed procedurally once the Articles of Confederation went into effect, as ratification did little more than constitutionalize what the Continental Congress had been doing. That body was renamed the Congress of the Confederation; but most Americans continued to call it the Continental Congress, since its organization remained the same. As the Confederation Congress attempted to govern the continually growing U.S. states, its delegates discovered that the limitations placed upon the central government (such as in assembling delegates, raising funds, and regulating commerce) rendered it ineffective at doing so. As the government's weaknesses became apparent, especially after Shays' Rebellion, some prominent political thinkers in the fledgling union began asking for changes to the Articles. Their hope was to create a stronger government. Initially, in September 1786, some states met to address interstate protectionist trade barriers between them. Shortly thereafter, as more states became interested in meeting to revise the Articles, a meeting was set in Philadelphia on May 25, 1787. This became the Constitutional Convention. Delegates quickly agreed that the defects of the frame of government could not be remedied by altering the Articles, and so went beyond their mandate by replacing it with a new constitution. On March 4, 1789, the government under the Articles was replaced with the federal government under the Constitution. The new Constitution provided for a much stronger federal government