In the last couple of months, I have come to realize that the cause of the war was money. The loss of huge amounts of it to North Eastern financial interests, and the acquisition of it by Southern Ports who would obtain a huge chunk of the European trade because of greatly lowered import tariffs.
Had the South succeeded in establishing trade with their stated tariff of 13% on imported goods, the Northern Tariff of 45% would be uncompetitive. Likewise the usage of NorthEaster shipping companies, Warehouses and textile factories would have gone a begging.
And Independent South would have been a devastating economic Hammer against the North East's financial security.
The war was started because they very badly needed to stop European Trade with the South. Allowing it would have wrecked the financial well being of the North East. This is why one of the first things they did was to create that Blockade. If the European powers had gotten a taste of normalized trade with the South, then they would have thrown their weight behind Southern Independence.
The war was in fact about money.
Here's a map to give you an idea of what was at stake from allowing an Independent South with lower import tariffs.
