Was the Gettysburg Address a political speech and why?

Lincoln's main motivation for this speech was to rally the Union to continue the war. He also wanted to communicate that the war was not about states rights or slavery, but for the preservation of democracy.

He could not have ignored, however, that his re-election was greatly helped by underscroring that the victory at Gettysburg represented a turning point in the war the occurred under his leadership. In this sense it was also a political speech.

Well said.

How do you know all this stuff?