The Yankees' Secret Weapon

[Steve]

Here's an image of the pardon in question, cropped from the court martial report. Notice something. There's a big notation below Lincoln's signature that says "G. O. 167 A.G.O." and dated "1864". If this was a case of forgery, what kind of idiot forger would think this was the document to alter, but leave the other date right below it?

   

Does anybody have information on General Order 167 of the Adjutant General Office which the notation refers to?