On March 5, 1770, the hyperbolically named Boston Massacre took place when British soldiers fired on a mob that had gathered to, essentially, talk smack to one of the soldiers stationed outside the Custom House. Five people died, and eleven were injured.
To be fair, the colonists should take the lion’s share of the blame for what happened. It all started when a wigmaker’s apprentice showed up at the Custom House to insult one of the officers. The officer ignored the insults, so the apprentice went and got a few of his buddies, who soon started throwing rocks at the officer, Captain Lieutenant Goldfinch. The private on duty, Hugh White, tried to get them to knock it off and eventually got into a fight with the apprentice, which just attracted a larger crowd. The crowd, which was full of colonists pissed off at England for basically treating the colonies like an ATM machine, got larger and uglier as the evening wore on. It grew to about 50 strong, prompting the officer of the day, Captain Thomas Preston, to dispatch seven or eight soldiers with bayonets fixed to try to keep order. Soon after the soldiers, along with Preston and his subordinate, James Basset, arrived, the crowd swelled to 3-400 people, who started throwing snowballs and small objects at the soldiers. A private was attacked with a club wielded by a tavernkeeper, and when he got back to his feet, he allegedly fired his musket. The incredibly stupid crowd started yelling “Fire!” at a group of outnumbered soldiers, who obliged. Three men died instantly, and two more died later. On March 27, Preston and four other soldiers were indicted for murder.
News of the event spread around the colonies and was used as a PR boost for colonists agitating for independence. They made up a lot of inflammatory details, like claiming Preston ordered his men to fire. Paintings and prints of the event started circulating, the most famous one done by silversmith and engraver Paul Revere (pictured).
There was some concern, after all this happened, about the soldiers having a chance at a fair trial. Preston wrote personally to John Adams, begging him to act as their defense attorney. Adams was a well-known Patriot, but also a lawyer who believed everyone should get a fair day in court. So, he took the case and, aided by two other lawyers, managed to get Preston acquitted on October 30, 1770. Six of the eight soldiers who were arrested were acquitted at their own trial, which started in November. The other two were found guilty of manslaughter and were branded on their thumbs in open court as punishment.