Abraham Lincoln gathered his cabinet to tell them he was going to issue the Emancipation Proclamation. He said he had made a solemn vow to the Almighty that if God gave him victory at Antietam, Lincoln would issue the decree.
Now, I've seen that story, variously quoted. I don't know the source for it; presumably it came from a member of the cabinet. But there are a couple of problems with Brooks' telling of it. The minor one is the reference to Antietam. It was, indeed, the Bloodiest Day which gave Lincoln the victory he needed to issue the Proclamation. But every history I've even read agrees that Lincoln had actually made the decision some weeks earlier, before Lee invaded Maryland.
That revisionism might be of no importance, but the larger problem is. In Brooks' tale Lincoln appears to be playing the Lotto with God. Victory at Antietam thus becomes some sort of confirmation of His existence to the famously doubt-filled Great Emancipator. It's a Parson Weems job, a sorry political hack turning a great and complex political leader into an elementary-school morality skit.
Here's what Lincoln said on September 13, the same day the Federals entered Frederick:
These are not, however, the days of miracles, and I suppose it will be granted that I am not to expect a direct revelation. I must study the plain physical facts of the case, ascertain what is possible and learn what appears to be wise and right.
I'll not waste time suggesting Brooks could do the same.