"Firing on that fort will inagurate a civil war greater than any the world has yet seen...At this time it is suicide, murder, and will lose us every friend in the North...You will wantonly srike a hornet's nest which extends from mountains to ocean, and legions now quiet will swarm out and sting us to death. It is unnecessary; it put us in the wrong; it is fatal." -- Robert Toombs to Jefferson Davis, April 1861
So The Davis knew exactly what would happen if he fired and he did it anyway. And Toombs was right. It was unnecessary, it did put the south in the wrong, and it was fatal. Lincoln didn't kill the confederacy, it was a victim of suicide and The Davis pulled the trigger.
In typical fashion for you, your conclusion is a...non-sequitur! Your premise, that Toombs advised against attacking based on his own personal prediction, does not necessitate your conclusion that Davis "knew" and invasion "would happen." Rather, it only indicates that in the mind of one of the participants in his government, an invasion was predicted at a time prior to that invasion occurring. Predictions sometimes come true, but they do not necessitate their own actualization. Try again.