What caused colonists to break away from Britain?

The reasons colonists separated from Britain are numerous. King George III would not let the colonists govern themselves. After the colonial protests against the Sugar Act and Stamp Act, Parliament passed the Declaratory Act, saying that the colonists had to do whatever Parliament said.

Britain would not allow colonists to trade with whoever they wanted. They believed in mercantilism, the theory that colonies exist for the sake of the mother country. Therefore they passed the Navigation Acts, a series of laws that made the colonists only allowed to trade with England. This upset the colonists. They wanted the right to choose who they sold to.

Also, to pay for the French and Indian War, they had to raise taxes on the colonies. They passed the Sugar Act, the first act that was passed to raise money, not control trade. King George and Parliament merely saw it as another tax, and a just one, but the colonies did not have any representatives in Parliament, and they saw it as unfair. Protesting and smuggling led to the Sugar Act being repealed, only to be replaced by the Stamp Act. That was when the Declaratory Act was passed.

After that came a succession of taxes, each disliked by colonists: the Townshend Acts, which taxed lead, paper, paint, tea, etc., and then the Tea Act, which came after colonial protests caused Parliament to repeal all of the Townshend Acts except the one on tea. This caused the Boston Tea Party.

To respond, Parliament passed the Intolerable Acts, which canceled the Massachusetts charter, closed Boston harbor, and forced colonists to quarter soldiers in their homes.

The last straw before fighting broke out was when the British tried to steal American guns and ammunition. Paul Revere and William Dawes warned the colonists, and they met the British in battle in Lexington and Concord.

Then King George ignored the Olive Branch Petition, a peace treaty sent by colonists.

All of these contributed to the writing of the Declaration of Independence. For a list by the colonists themselves, read the second section of the Declaration.