On Friday evening, the 16th of September, I learned that Mr. Shields and Gen. Whiteside had started in pursuit of Mr. Lincoln, who was at Tremont, attending court. I knew that Mr. Lincoln was wholly unpractised both as to the diplomacy and weapons commonly employed in similar affairs; and I felt it my duty, as a friend, to be with him, and, so far as in my power, to prevent any advantage being taken of him as to either his honor or his life. Accordingly, Mr. Butler and myself started, passed Shields and Whiteside in the night, and arrived at Tremont ahead of them on Saturday morning. I told Mr. Lincoln what was brewing, and asked him what course he proposed to himself. He stated that he was wholly opposed to duelling, and would do any thing to avoid it that might not degrade him in the estimation of himself and friends; but, if such degradation or a fight were the only alternative, he would fight. In the afternoon Shields and Whiteside arrived, and very soon the former sent to Mr. Lincoln by the latter the following note or letter:-- Tremont, Sept. 17,1842. A. Lincoln, Esq.--I regret that my absence on public business compelled me to postpone a matter of private consideration a little longer than I could have desired. It will only be necessary, however, to account for it by informing you that I have been to Quincy on business that would not admit of delay. I will now state briefly the reasons of my troubling you with this communication, the disagreeable nature of which I regret, as I had hoped to avoid any difficulty with any one in Springfield while residing there, by endeavoring to conduct myself in such a way amongst both my political friends and opponents, as to escape the necessity of any. Whilst thus abstaining from giving provocation, I have become the object of slander, vituperation, and personal abuse, which, were I capable of submitting to, I would prove myself worthy of the whole of it. In two or three of the last number's of "The Sangamon Journal," articles of the most personal nature, and calculated to degrade me, have made their appearance. On inquiring, I was informed by the editor of that paper, through the medium of my friend, Gen. Whiteside, that you are the author of those articles. This information satisfies me that I have become, by some means or other, the object of your secret hostility. I will not take the trouble of inquiring into the reason of all this; but I will take the liberty of requiring a full, positive, and absolute retraction of all offensive allusions used by you in these communications, in relation to my private character and standing as a man, as an apology for the insults conveyed in them. This may prevent consequences which no one will regret more than myself. Your ob't serv't, [Copy.] Jas. Shields. About sunset Gen. Whiteside called again, and received from Mr. Lincoln the following answer to Mr. Shields's note:-- Tremont, Sept. 17, 1812