If you read Lincons speaches and letters along with the editorial of most of the Northern newspapers, abolition did not become a major "cause" untill 1862. This was in part to try and keep the British from being more favorible to the South's cause. Slavery had long been outlawed in GB. In fact several letter from old Abe clearly spell out that he would gladly accept the states in succession back into the union with slavery in tact. Not untill not 1862 does this seem to be dropped.

The PC people of the world will insist that the only reason for the Civil Wars was slavery. Tarrifs had more direct cause than slavery in many ways. The north wanted high tarrifs to protect their new industry while the south, which had little industry wanted no tarrifs so they could by cheap goods. Facts are often inconvient and sometime down right bad for popular viewpoints.

Now I agree that slavery was a blight on the US. It should have been eliminated much earlier. But it always came down to money. If the Federal government "liberated" the slaves would they pay the owners for their property? Under the constitution slaves were legal property and if conficasacted the owner were due compensation. Slave owners were not about to set free a large part of their wealth. Even if it was getting cheaper by the day.

Until the land was "cottoned out" the slaves made their owners money. After that time many of the slaves were sold to areas which had not been depleated. They were down in the deeper south, hence the term "sold down the river". Slave prices had been in steady decline in VA for 20 years. And the real truth is that 99% of the south owned no slaves.

By the way, your blockaid would have lasted about a month if the cotton crop failed in India. The British navy would have opened the ports in a heart beat to keep the mills in GB running. Then the war would have ended differently. British and French wares would have kept the South alive and made it impossible for the North to prevail. Lincoln would have lost in 1864 to the Little General and the North would have sued for terms. Slavery would have still died, but you are right a few diehards would have tried to make it last as long as they could. All in all the war turned out fine but I wish that State rights was a little stronger these days.