The Boston Massacre occurred on March 5, 1770, when British soldiers fired into a crowd of colonists who had been throwing snowballs at the soldiers. The altercation was instigated because the soldiers, who were being quartered in Boston, were taking jobs the from the colonists. The Massacre began when a soldier shot Crispus Attucks and resulted in the deaths of four other colonists.
At the trial of the British solders involved in the massacre, the defendants were represented by John Adams. Adams' defense of the soldiers lead to the acquittal of six of the eight charged and the conviction of the remaining two on charges of manslaughter, rather than murder. Their punishment was to have their thumbs branded. Near the end of his life Adams described his defense of the British soldiers as "one of the most gallant, generous, manly, and disinterested actions of my whole life, and one of the best pieces of service I ever rendered my country." 
The Boston Massacre created further animosity between the colonists and the British leading up to the American Revolutionary War, and was followed by other important incidents, such as the Gaspee Affair and the Boston Tea Party.