That is no surprise and has nothing to do with peacetime revenue collection, which is the question, as I understood it, that George asked about the loss of revenue being a secondary cause.
The United States government was overspending the federal budget by over 300% taking in only $600,000.00 a day in revenue while spending $2,500,000.00 a day on the war. So we are talking Northern Wealth at the expense of deficit spending.
Cannons cost money and I am sure that increased industry would generated increased revenue. Lets not forget that many arms were also bought overseas. And that in effect the United States also armed the Confederate Army with all the weapons that were left on the battlefield and captured early in the war. You said yourself the Northern prosperity collaped after the war when there was no need for all that war production.
And lets not forget that Lincoln also instituted an Income Tax to increase his revenue. Is that the type of "Increased Wealth" we are talking about as a measure of success without the revenue generated by foriegn sales to the south?