White House Chief of Staff John F. Kelly, whose boss is well known for unique opinions about the Civil War, introduced his own hypothesis to the world last night when he blamed the war on “the lack of an ability to compromise.”

The Washington Post has already written about what historians think of Kelly’s thoughts, their assessments ranging from “dangerous” to “kind of depressing.”

But the truth is, the panicky months before the Civil War were full of attempts to compromise with the rebellious South.

The most popular proposal, by far, was a constitutional amendment that would have irreversibly immortalized slavery as a feature of the United States.

And while supporters of this compromise — up to and including Abraham Lincoln and most of Congress — did fail to pull it off, it wasn’t for lack of trying.

“Mass panic”

The central difficulty of bargaining with secessionists, as Daniel W. Crofts writes in “Lincoln and the Politics of Slavery,” is that so many secessionists were hysterical.

“White Southerners had heard endlessly that ‘Black Republicans’ planned to destroy slavery and confer equal citizen rights on ex-slaves,” the College of New Jersey’s emeritus history professor writes in his book. So when Lincoln was elected as the first Republican president in late 1860, “an extensive mass panic” followed.

“The Government is in the hands of those who are unfriendly to Slavery,” a U.S. senator from Georgia warned Congress the next month, for example. He prophesied not just abolition — but slave uprisings, “murderings, poisonings, and revolts” under Lincoln’s reign.

“Which was absolute garbage,” Crofts told The Washington Post. “Lincoln hated slavery,” the professor said — but the incoming president had no desire to upend the Southern slave economy, lest he fracture his young party or risk a war.

Nevertheless, fear spread. And as Southern states started to secede, Unionists in the north urged Lincoln to compromise.

Petitions descended on Washington from Boston, New York City and Philadelphia, Crofts writes. The largest daily newspaper in the world, the New York Herald, implored Lincoln to strike “a Union compromise” that would put an end to the notion that his party wanted to “exterminate the white race in the South and set the negro free.”

Lincoln, it turned out, was amenable.

[Kelly calls Robert E. Lee an ‘honorable man’ and says ‘lack of compromise’ caused the Civil War]

A conspiracy to compromise

While fantasies of freed slaves running rampant drove politics in the South in 1860, policymakers in Washington debated a relatively narrow issue: whether to allow slavery on the U.S. frontiers.

“The right to take slaves to the territories was a defining symbol of Southern equality in the Union,” Crofts writes. But Republicans, Lincoln included, drew their line here; they would condone slavery where it existed, but not allow its expansion.

Thurlow Weed, the politically connected editor of the Albany Journal, spent the end of 1860 publishing essays that Crofts calls “trial balloons” for his friends in Washington — to test whether Lincoln might be open to compromise on the frontier slavery issue.

“Our Fathers found Slavery so deeply seated … that they could not form a Union without recognizing and tolerating it,” Weed wrote in mid-December, according to Crofts. He advocated a widely circulated plan called the Crittenden Compromise, which would allow slavery in new southern territories only.

Weed published this essay and then hopped on a train to Springfield, Ill., to ask president-elect Lincoln what he thought of the idea.

Lincoln didn’t think much of it, Crofts writes: “He would not bend an inch toward them on the territories.”

But the historian cites evidence that Lincoln offered Weed a different sort of compromise in that meeting.

It’s in a Dec. 26 letter to Lincoln from Sen. William Henry Seward of New York — a high-ranking member of the Republican Party with whom Weed often conspired.

Seward had been working with other senators to head off the South’s secession movement. He told the president-elect that his committee’s proposal was modeled off “the suggestions made by you, through Mr. Weed, as I understand it.”

The first proposal: “That the Constitution should never be altered, so as to authorize Congress to abolish or interfere with slavery in the States.”

[The day white Virginia stopped admiring Gen. Lee and started worshiping him]

“Lincoln’s fingerprints”

Seward drafted a constitutional amendment that same week, which can now be seen at the National Archives.

It’s short, written in immaculate cursive, and signed by outgoing president James Buchanan.

And as Crofts notes, the world “slavery” does not appear on it even once:

“No amendment shall be made to the Constitution which will authorize or give to Congress the power to abolish or interfere, within any State, with the domestic institutions thereof, including that of people held to labor or service by the laws of said State.”

But slaves were exactly what was meant. The amendment would have assuaged slave owners’ fears by forever forbidding the federal government from freeing them.

“It would be a formula for reuniting the country politically,” Crofts said, aimed not so much at hardcore secessionists in the Deep South, but to convince people in “border” states such as Virginia that Lincoln had no designs on their slaves.

“Lincoln’s fingerprints are on this thing,” Crofts told The Post. Not only did he probably suggest its creation, but he spent the days leading up to his inauguration trying to rally Congress behind it.

[Jefferson Davis: The Confederacy’s first, worst and only president]

“Perpetual bondage”

The slavery amendment — it would have been the 13th — divided Congress almost as soon as it was introduced.

“A mass of humanity jammed the hallways” of the Senate building in January to hear Seward pitch his plan, Crofts writes. Two days later, Rep. Thomas Corwin of Ohio reported on his House committee’s version of the amendment, which his fellow Republicans refused to support.

Two congressmen, Crofts writes, condemned the bill as a “constitutional decree of perpetual bondage.” Another lectured Republicans that to “vote for compromise” was to “sow, on soil now free, the seeds of whips, chains, theft, robbery, and murder.”

Corwin despaired of ever passing the amendment through Congress — let alone of then convincing state legislatures to ratify it, Crofts writes.

The congressman warned Lincoln that “a long and bloody civil war must follow” if they failed.

And so, less than two weeks before his inauguration, just after dawn on Feb. 23, 1861, Lincoln arrived by train in Washington and gave the bill a very powerful push.

“Quid pro quo”

So bad was secession fervor by then that Lincoln traveled incognito, Crofts writes, lest assassins kill him on the way.

On his second day in Washington, Crofts writes, Lincoln met privately with the slavery amendment’s House champion, Corwin, and “gave him the go ahead” to initiate a vote.

The next week was filled with chaotic late-night sessions and nail-biter votes in both the House and the Senate. Crofts cites newspaper reports of insider political gossip to argue that “Lincoln undoubtedly worked behind the scenes to get the amendment passed.”

The historian even sees signs that “some kind of quid pro quo” might have won several last-minute votes for the bill, which needed a two-thirds majority in each chamber.

Take Sen. Lot M. Morrill of Maine, who complained aloud that the amendment would change the “whole sprit” of the Constitution — then inexplicably came out in support of it hours later, Crofts writes.

Or Thomas Theaker, a lame-duck congressman who withheld his vote on Feb. 27, then voted for the bill in a redo the very next day, and was subsequently appointed to a U.S. Patent Office board.

Whatever happened, it worked. A cheering crowd and a marine band marched to Lincoln’s hotel after the House passed the amendment on Feb. 28, Crofts writes.

“The president-elect responded graciously by promising to overcome all current ‘misunderstanding.’ ”

[The truth about Confederate Gen. Robert E. Lee: He wasn’t very good at his job]

“I have no objection”

A few days later, after an extraordinary session that lasted nearly the entire weekend, the Senate passed the amendment by a single vote at 5:20 a.m. Monday.

Eight hours later, the new president of the United States stood in front of the U.S. Capitol, took an oath and gave his inaugural address to a splintering nation.

“I have no purpose, directly or indirectly, to interfere with the institution of slavery in the States where it exists,” Lincoln promised in his opening lines.

And toward the end, in a passage Crofts said was “slipped in”:

“I understand a proposed amendment to the Constitution — which amendment, however, I have not seen — has passed Congress.”

Lincoln quoted the resolution’s text — slavery everlasting, if not in so many words — and gave this endorsement to the crowd:

“Holding such a provision to now be implied constitutional law, I have no objection to its being made express and irrevocable,” he said.

War breaks out

And so it might have been, irrevocable, had not a war come first.

President Lincoln and Seward — who had drafted the amendment as a senator and was now the secretary of state — sent its text to the governors of every state in the splintering Union, to await ratification by their legislatures, Crofts writes.

The newspapers sounded optimistic, for a while. The Louisville Journal wrote that the compromise “will go far toward satisfying the South.”

But the conflict was already spiraling out of control by them, and Lincoln’s attention was soon diverted to a crisis at Fort Sumter, where the Civil War was launched in April.

Kentucky had managed to ratify the slavery amendment by then, Crofts writes. Ohio and Rhode Island would do so in the bloody weeks to follow, but it was too late.

“Because the amendment was designed to prevent a war, it became irrelevant once the war broke out,” Crofts writes. “Before long, Northerners who never could imagine using armed force against the slave system found that war forced them to do just that.”

The Civil War made real what had been a secessionist fantasy weeks earlier: It turned Republicans into abolitionists. And in the final year of the war, the South nearly defeated, Lincoln pushed for a very different 13th Amendment than the one he first endorsed.

This one was actually ratified, and it abolished slavery forever — the antithesis of an abandoned compromise.

Read more:

Historians respond to John Kelly’s civil war remarks: ‘Strange,’ ‘sad,’ ‘wrong’

‘Why was there the Civil War?’ Here’s your answer.

Five myths about why the South seceded

The day white Virginia stopped admiring Gen. Robert E. Lee and started worshiping him