Following the 7 Years War (1756-63), Britain levied a series of taxes on the American colonies to help pay for them. The colonists responded with protests, including the (slightly misguided) ‘Boston Tea Party’. British government crackdowns ensued, militia were mustered, and eventually there was war.
Tax protests meant boycotts of British imports. In order to ensure everyone joined these boycotts, the rebellious colonists set up ‘Committees of Compliance’ whose job was to monitor and enforce compliance, thus acquiring some characteristics of a government. When fighting broke out in 1775, the Maryland committee helped to set up the Continental Congress, which drafted the Declaration of Independence.
The new constitution, inspired more by the thinkers of the relatively conservative British Enlightenment than the more radical French, was not revolutionary. The interests of wealthy landowners were protected and slaves were not emancipated.
What was revolutionary was the way the Americans achieved independence. They threw off the British monarchy and forged their own government without a king, and so without social classes. In the new nation, free people regarded one another as equal.