I didn't make that claim. If you will check post 98, you'll see that I said the Northern objective during the first two years of the war was to preserve the Union, not end slavery.
Here is what Lincoln said in 1862 [Link]:
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.
Of course, even then it was for many, perhaps most, based more on a desire to punish the slaveocrats who started the war and caused so much suffering than on a feeling of brotherhood for the black man.
In 1861, Northern politicians realized that the border states might secede if they announced that the war was to free the slaves.
You may be right about a Northern desire to punish the South. It may explain things like the 18-month long bombardment of Charleston SC civilians by Union forces.
Or maybe the nature of a siege in warfare better explains the bombardment. War is rough. Maybe the idiot hotheads of Charleston should of thought of that before they troubled the nation. The British bombarded Charleston in the Revolution. Should have been no surprise.