The United States Declaration of war was not a happy, or peaceful one; as can be found through the very definition of the word "war." The United States had no interest in getting involved in the militant disputes of the Europeans, and were not happy to be dragged in to war by Germany. It is clear that they were not happy with the German government. They sought neutrality, and the peace of the world, but had no interest in going to war. The tone of their deceleration was likely one of anger, and of distress. They had no business in this war, and they knew that.
The Germans on the other hand; well, this was exactly what they wanted. They wanted the U.S. in this war; they wanted the United States. Their response to the declaration of war against them was probably something similar to a modern day "bring it on." They wanted the U.S. to bring the battle to them, and hoped that that was exactly what they would do.
