The Declaration of Independence made America an independant nation and symbolized their freedom. They wouldn't have to answer to a king and could govern themselves.
The United States Constitution outlined the rights of Americans and was specially catered to the needs and wants of the american people. It was the document that gave the people their rights.
Abraham Lincoln was an abolitionist and his presidency was most know for the end of slavery and giving people of color rights.
Before the Civil War people of color had no rights at all. They were forced into slavery and treated like property.
After the civil war and the 13th amendment slavery was outlawed and many people now gained rights and could follow their own free will.