In researching the Civil War, I've seen a quote, attributed to Abraham Lincoln, come up several times. The most complete version of the quote I have found comes from this website which gives the quote as follows:
See… what a lot of land these fellows hold, of which Vicksburg is the key. Here is Red River which will supply the Confederates with cattle and corn to feed their armies. There are the Arkansas and White Rivers, which can supply cattle and hogs by the thousand. From Vicksburg these supplies can be distributed by rail all over the Confederacy. Then there is the giant depot of supplies on the Yazoo. Let us get Vicksburg and all that country is ours. The war can never be brought to a close until that key is in our pocket. I am acquainted with that region and know what I am talking about.
The website also claims that the quote comes from Abraham Lincoln while he was "explaining how important Vicksburg was to the Confederacy. Lincoln was pointing at a large wall map in General George B. McClellan’s headquarters during a secret planning meeting to take New Orleans with Rear Admiral David Dixon Porter and General McClellan".
This quote feels suspicious to me because I cannot find any information about this "secret meeting", like when it occurred. Also, if the meeting was supposed to be secret, how has this quote been preserved?
I would really appreciate it if someone could identify where this quote was first recorded, or at least when Lincoln supposedly gave this quote.