Because one person doing something wrong, completely justifies another person doing something wrong.
Or was the invasion a direct result of Germany starting the war in the first place?
You may not be aware of this, but Germany did in fact declare war on us. Congress then moved to declare war on Germany. It was more constitutionally lawful than the Civil War, which did not receive a congressional declaration of war, as outlined in the Constitution.
Are you saying you were wrong resorting to the Nazi analogy?
You may not be aware of this, but Germany did in fact declare war on us. Congress then moved to declare war on Germany.
And the Confederacy initiated the conflict by firing on Sumter. Any invasion, as you term it, would not have happened had they not done so. Likewise Germany initiated the war. Any invasion would not have happened had they not done so. In neither case can the invader be called the aggressor.
It was more constitutionally lawful than the Civil War, which did not receive a congressional declaration of war, as outlined in the Constitution.
You declare war on other countries. The Confederacy was not a sovereign country, not in the eyes of the U.S. or the rest of the world. They were, in the eyes of the U.S. and the rest of the world, a rebellious part of the United States. One does not declare war on oneself in order to quell a rebellion. It was more constitutionally lawful than the Civil War, which did not receive a congressional declaration of war, as outlined in the Constitution.