Lincoln's Letter to the Editor of the N,Y, Tribune

I do not doubt that slavery was a cause of the US Civil War, but it was President Lincoln's expressed primary objective as he wrote to the editor of the New York Tribune was to Preserve the Union. It was the South's fear that Lincoln would free the slaves, but it appears, based on the letter he wrote  to the editor of the New York newspaper, that this was a misjudgement by the South of Lincoln and his objective.
The institution had existed f0r over 2 centuries in the South, the question is would there have
been war had the South _n0t_ succeeded? The succession of Carolina followed by the attack on Ft. Sumter started the Civil War.
I had read, believed and defended the opinion that unfair tariffs imposed on the South was the main cause of the war, but this was proven wrong, in spite of the cites on the net advocating this fraud.
Lincoln's Letter to the editor of the New York Newspaper was written 1n August 22, 1862,  ab0ut a year and a half after the start of the War between the States:
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Mathew Brady Photographs of Civil War-Era Personalities and Scenes, National Archives and Records Administration
Hon. Horace Greely: Executive Mansion,
Dear Sir Washington, August 22, 1862.
I have just read yours of the 19th. addressed to myself through the New-York Tribune. If there be in it any statements, or assumptions of fact, which I may know to be erroneous, I do not, now and here, controvert them. If there be in it any inferences which I may believe to be falsely drawn, I do not now and here, argue against them. If there be perceptable in it an impatient and dictatorial tone, I waive it in deference to an old friend, whose heart I have always supposed to be right.
As to the policy I “seem to be pursuing” as you say, I have not meant to leave any one in doubt.
I would save the Union. I would save it the shortest way under the Constitution. The sooner the national authority can be restored; the nearer the Union will be “the Union as it was.” If there be those who would not save the Union, unless they could at the same time save slavery, I do not agree with them. If there be those who would not save the Union unless they could at the same time destroy slavery, I do not agree with them. _My_paramount_object_in_this_struggle_is_to_ save_ the_ Union_, and is not either to save or to destroy slavery. If I could save the Union without freeing any slave I would do it, and if I could save it by freeing all the slaves I would do it; and if I could save it by freeing some and leaving others alone I would also do that. What I do about slavery, and the colored race, I do because I believe it helps to save the Union; and what I forbear, I forbear because I do not believe it would help to save the Union. I shall do less whenever I shall believe what I am doing hurts the cause, and I shall do more whenever I shall believe doing more will help the cause. I shall try to correct errors when shown to be errors; and I shall adopt new views so fast as they shall appear to be true views.
I have here stated my purpose according to my view of official duty; and I intend no modification of my oft-expressed personal wish that all men every where could be free. Yours,
A. LINCOLN
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