The Navigation act of 1817. Couldn't use foreign ships or crews. Had to use the New York/North Eastern shipping companies which pretty much controlled all shipping.
Mail and cargo carrying subsidies paid to them by the Federal government made it harder for Southern based shipping companies to compete.
the Navigation act of 1817 was passed in retaliation for the British closing their Caribbean ports to American ships.
Not as a measure to stick it to the South. Nothing in the Navigation act requires the use of New York or Northeastern shipping companies.
How on earth did he get secret orders from the President to disrupt the Sumter expedition and try to start a war in Florida? Lincoln said it was all an error, and that he signed so many documents, he didn’t realize he was tasking the ship to be in two places at once, and this might be believable were it not for the fact that these were hand carried “secret” orders, not routine ship orders.
How does one forget that one wrote specific secret orders relieving a specific Captain (Captain Mercer) of duty, and handing his powerful warship to a Lieutenant? And why did they need to be secret?
From what I have read, Seward drafted the order and Lincoln signed it. When Welles found out about the change to Powhatans’s orders, he demanded Seward and he, discuss the issue with Lincoln. When the discussion ended, Lincoln directed Seward to countermand the original set of orders and direct Powhatan to join the Sumter expedition. Seward did as directed, he sent an order to Porter to join the Sumter expedition. Those orders were delivered to Porter as Powhatan sailed. Porter read the order, and chose to disregard them because only Seward’s name was on the order, and he was not in Porter’s chain of Command. Seward seems to have injected himself in some affairs that were not his to deal with, and for some reason Lincoln allowed that to happen. Lincoln did apologize to Welles, later.
As far being secret was concerned. Welles had advised Lincoln that he had serious doubts about the loyalty of a fair number of the Navy Department staff. The fact that officials in Charleston knew about the details of the resupply mission, that seems to have been the case.