[BroJoeK]

PeaRidge quoting a Boston newspaper 3/18/1861: "It does not require extraordinary sagacity to perceive that trade is perhaps the controlling motive operating to prevent the return of the seceding States to the Union."

That was just mindless blather by people addicted to wishful thinking.
In fact, there was, literally, nothing in March of 1861 which the Union might do to entice Deep South states back into Union.
By this time numerous proposals had been made in Congress and elsewhere for change to attract secessionists, but all that time the Confederacy was instead busy provoking and preparing to start war at Fort Sumter.
It made no response to any such ideas.

Tariffs did not drive away the Deep South, and no change to tariffs in March 1861 was going to bring it back.

[DiogenesLamp]

Thanks in part to people like Robert E Lee, slavery is gone now - gone for good- and no amount of arguing is going to bring it back.

I beg to differ. While we are arguing, that is exactly what they have been doing.

[PeaRidge]

You misread the newspaper account. You should pay more attention to it since that author of the time understood better the situation then than you do now, 150 years later.

On the very day of that editorial, Southern peace commissioners were still in Washington to negotiate peace. The Virginia Peace conference had just concluded. Lincoln invited a representative from Virginia to visit his office and discuss Ft. Sumter. When that Virginian arrived and advised Lincoln not to send ships to Charleston, Lincoln advised him that he was too late.

At that time, tariffs were not a problem for the Confederacy, but was the problem for Lincoln.