Here are a few examples:
1611--the King James Version of the Bible was published, making it possible for English-speaking people to read the Bible for themselves.
1620--the Mayflower Compact was written, establishing a form of government for the colony.
1650--it was not enlightening, but this event has had a tremendous effect on American history: slavery is made legal in the colonies.
1776--the American Revolution and the Declaration of Independence gave birth to the United States.
1789--the French Revolution destroyed the monarchy, weakened the aristocracy, and established (except for the reign of Napoleon and a couple of others), a form of government based on citizenship and the rights of the people.
I hope this helps you. Other editors will give you different examples, I'm sure.