The Boston Tea Party has its roots in the Tea Act of 1773, which gave the British East India Company, which was struggling financially, the right to sell tea to the American colonies without paying taxes to the British government. American colonial merchants, who did have to pay taxes on tea arriving in their ports, were furious at the unfair protection given the East India Company, especially when they had no representation in the British government (thus the famous rallying cry: No taxation without representation!)
These merchants began to pressure tea agents to abandon their support for the company and, led by Samuel Adams, to organize protests against the tea tax. When Massachusetts Governor Hutchinson refused to let three ships in the Boston Harbor leave without paying taxes, the colonists took matters into their own hands more firmly.
On December 16, 1773, 150 men disguised as Mohawk tribe members boarded the three ships, the Dartmouth, the Eleanor and the Beaver, hacked open all of the 342 tea caskets with axes, and threw it in its entirety into the Boston Harbor. They also took off their shoes and threw these into the harbor to make sure they could not be connected to the crime.
To punish the colonists, Great Britain ordered the Boston port closed until England was paid for the tea. This was one of four punitive measures that together were called the Intolerable Acts by the colonists.