Don't mix these two things up. GDP is not European trade. European trade is part of GDP, but it is not the same thing.
The South was producing the bulk of European Trade, which was about 278 million dollars per year in 1860.
GNP and cotton was only a portion of that. Industry accounted for 28% of GNP and services provided another 34%.
Gross National Product is not the issue here. Only European trade is the issue. Were taxes collected on GNP? Then why talk about it? Taxes (tariffs) were only collected on Imports, therefore imports were the sole source of revenue for the US Government.
Imports were paid for by exports, 73% of which were products of the Southern states.
Show me your figures for how much export value the North created. (Do not include specie. Goods purchased with specie are not "trade", and a nation that continues to use specie to purchase goods will soon run out of specie.)
Why dont you talk about the $4 billion in assets that slaveholders feared losing if slavery was outlawed, and how that fear manifested in the election of Abraham Lincoln in 1860. Why dont you talk about the seccesion documents of the southern states who justify rebellion not on tariffs but on the institution of slavery.
What did the U.S. export in 1863-64 that generated the $113 million in tariff revenue?