Answer:
1. British troops arrive in the American colonies.
In response to increased agitation for independence amongst the American colonies, the British government sent British troops the the American colonies to quell rebellion.
2. Colonial militia takes positions in Massachusetts.
When the British arrived they found the the colonial militia had already taken up positions in Massachusetts.
3. British troops fire upon the colonial militia.
In a moment of confusion, the British fired on the militia and killed some men as a result.
4. The colonial militia fire upon the British troops.
The colonial militia then returned fire on the British and killed and wounded some of them.
5. War between the British and American colonies officially begins.
Thus began the American revolution.