The result is not doubtful. We shall not fail—if we stand firm, we shall not fail. Wise councils may accelerate or mistakes delay it, but, sooner or later the victory is sure to come. (124-126)

The last three sentences of this speech end on a surprisingly motivational note. Honest Abe pumps you up.

Lincoln has spent pages outlining the recent history of the slavery issue, to explain why the northern states might soon have to allow slavery within their borders. Scary stuff, right? He has some compelling arguments, too.

Then, at the end, he brings around by confidently asserting that he believes the United States will become all free.

We shall not fail – if we stand firm, we shall not fail. (125)

Heck yeah, Abe!

After all the stuff about how the north could be doomed to become slave states, he finishes on a positive note. As long as the anti-slavery forces stay strong, they will succeed. He's especially confident because of the rapid rise of the Republican Party over the past two years.

It's generally important in situations like this to give your audience some hope. Otherwise, why would they bother fighting anymore? The speech is quite serious and sometimes paints a depressing picture of the national state of affairs, but ending on an inspirational note can ensure that the audience remembers that all-important feeling of "things suck right now, but we can fix it."