When the American colonies declared their independence from Britain in 1776, they drafted the Articles of Confederation' to bind themselves together as unified country. These Articles, however, came with some drawbacks. For a start, they created a federal government which was subservient to the state legislatures. The Articles gave Congress certain powers, over foreign over policy, finance and internal disputes, but it was the individual states who really had the final say. On the issue of defense, for instance, Congress could theoretically declare war and raise an army but it had no way of forcing states to provide a quota of soldiers or pay for the necessary arms and equipment - should a state refuse.
The Articles didn't enable the federal government to collect taxes, either, and this was another major problem. Within a few years, Congress was plagued by debt and the states reacted by printing their own money. They used this to pay off veteran soldiers and a number of other creditors but the money was essentially worthless because the national economy was in such a poor state.