Long before he was inaugurated as President, Abraham Lincoln had expressed his views on the secession movement in the Southern states and his belief on what should happen if various forts were to come under the control of the secessionists. Judging by Lincoln's own private correspondence, he had made up his mind to use force if necessary, even if the Buchanan administration allowed the transfer into Southern hands. All letters or quotes from letters can be found in the Collected Works of Abraham Lincoln. Volume 4.
https://quod.lib.umich.edu/l/lincoln/lincoln4/
From Lincoln's own words, there was no room for compromise, and no interest in talking with the secessionists, and he certainly had military force on his mind.
Private & Confidential. Hon. Thurlow Weed Springfield, Ills- Dec. 17-1860
My dear Sir Yours of the 11th. was received two days ago. Should the convocation of Governors, of which you speak, seem desirous to know my views on the present aspect of things, tell them you judge from my speeches that I will be inflexible on the territorial question; that I probably think either the Missouri line extended, or Douglas' and Eli Thayer's Pop. Sov. would lose us every thing we gained by the election; that filibustering for all South of us, and making slave states of it, would follow in spite of us, under either plan.
Also, that I probably think all opposition, real and apparant, to the fugitive slave [clause] of the constitution ought to be withdrawn.
I believe you can pretend to find but little, if any thing, in my speeches, about secession; but my opinion is that no state can, in any way lawfully, get out of the Union, without the consent of the others; and that it is the duty of the President, and other government functionaries to run the machine as it is. Yours very truly A. LINCOLN---
Confidential
Hon. F. P. Blair, Ser. Springfield, Ills.
My dear Sir Dec. 21. 1860
Yours giving an account of an interview with Gen. Scott, is received, and for which I thank you. According to my present view, if the forts shall be given up before the inaugeration, the General must retake them afterwards. Yours truly A. LINCOLN
Confidential
Hon. A. G. Curtin Springfield, Ills.
My dear Sir Dec. 21. 1860
Yours of the 14th. was only received last night. I am much obliged by your kindness in asking my views in advance of preparing your inaugeral. I think of nothing proper for me to suggest except a word about this secession and disunion movement. On that subject, I think you would do well to express, without passion, threat, or appearance of boasting, but nevertheless, with firmness, the purpose of yourself, and your state to maintain the Union at all hazzards. Also, if you can, procure the Legislature to pass resolutions to that effect.
Confidential
Hon. E. B. Washburne Springfield, Ills.
My dear Sir: Dec. 21. 1860
Last night I received your letter giving an account of your interview with Gen. Scott, and for which I thank you. Please present my respects to the General, and tell him, confidentially, I shall be obliged to him to be as well prepared as he can to either hold, or retake, the forts, as the case may require, at, and after the inaugeration. Yours as ever A. LINCOLN
Confidential Major David Hunter, Springfield, Ills., Dec. 22, 1860.
My dear Sir: I am much obliged by the receipt of yours of the 18th. The most we can do now is to watch events, and be as well prepared as possible for any turn things may take. If the forts fall, my judgment is that they are to be retaken. When I shall determine definitely my time of starting of Washington, I will notify you. Yours truly, A. LINCOLN.
Hon. Lyman Trumbull Springfield, Ills. Dec. 24, 1860
My dear Sir I expect to be able to offer Mr. Blair a place in the cabinet; but I can not, as yet, be committed on the matter, to any extent whatever.
Despaches have come here two days in succession, that the Forts in South Carolina, will be surrendered by the order, or consent at least, of the President.
I can scarcely believe this; but if it prove true, I will, if our friends at Washington concur, announce publicly at once that they are to be retaken after the inaugeration. This will give the Union men a rallying cry, and preparation will proceed somewhat on their side, as well as on the other. Yours as ever A. LINCOLN
Private
Col. J. W. Webb. Springfield, Ills.
My dear Sir: Dec. 29. 1860
Yours kindly seeking my view as to the proper mode of dealing with secession, was received several days ago, but, for want of time I could not answer it till now. I think we should hold the forts, or retake them, as the case may be, and collect the revenue. We shall have to forego the use of the federal courts, and they that of the mails, for a while. We can not fight them in to holding courts, or receiving the mails.
This is an outline of my view; and perhaps suggests sufficiently, the whole of it. Yours very truly A. LINCOLN