The Chicago Daily Times expressed the prevailing sentiment of the north in an editorial dated March 2nd 1861 and titled “WHAT SHALL WE DO FOR REVENUE.” 

“That either the revenue from duties must be collected in the ports of the rebel states or the port must be closed to importations from abroad is generally admitted. If NEITHER of these things be done, our revenue laws are substantially repealed; THE SOURCES WHICH SUPPLY OUR TREASURY WILL BE DRIED UP; there shall be no money to carry on the government; the nation will become bankrupt before the next crop of corn is ripe. 

There will be nothing to furnish means of subsistence to the army; nothing to keep our Navy afloat; nothing to pay the salaries of the public officers; the present order of things must come to a dead stop.”

And all the time they were only after Southern money. That's not what I read in their history books.