The Boston Massacre occurred on the night of March 5, 1770. After all was said and done, the British soldiers who fired into the crowd killed five colonists. While this killing was unfortunate, it clearly was not a massacre. However, the colonists took this action and turned it into a huge propaganda event.
There was a growing dissatisfaction with British rule. Tax laws were being passed without the colonists having a say or vote on these laws. Colonists felt their rights were being violated. The British began to search the colonists to try to cut down on smuggling. Writs of assistance were legal. Thus, the events of March 5, 1770, gave the colonists a chance to capitalize on a British error.
Those colonists who were in favor of reducing British control decided that by exaggerating this event, they could get more support for their position. It still was too early to start talking about independence, but more people were becoming fed up with the British. By calling this event a massacre, this would give more support and sympathy to those in favor of curtailing British power.
The Boston Massacre could be viewed as the starting point for people to think about becoming free from British rule. Those who wanted that to occur used this event to their advantage.