First impressions are said to be lasting impressions, and indeed, it is remarkable how soon the New World "that was never before known to anyone" was viewed as a land of wealth, promise, and opportunity
What was common is that they were both fought as plans of Lee to move the fighting no Northern Parts of the federation. Antietam ended in a draw, while Gettysburg became a victory for the Union.
Many countries looked toward a more cooperative world by creating league of nations