In the Gettysburg Address "The sentence now we are engaged in a great civil war testing whether that nation or any other nation so conceived and so...

In the Gettysburg Address "The sentence now we are engaged in a great civil war testing whether that nation or any other nation so conceived and so dedicated can so long endure. We are met on a great battlefield of that war. "

Does this sentence and the first paragraph represent 1, the counterclaim, 2, introduce the topic and hooks the audience, 3, and give the speakers history for common ground, or 4) provides a transition between arguments?

Thanks so very much.