Thanksgiving arrives just when we need it — our most unifying holiday, at one of the most divisive moments in recent American history.

In general, the holiday is celebrated the same way around the country, which is among its best qualities. There are no blue-state versions and red-state versions. We all experience roughly the same routine as we go in and out of the annual food coma, punctuated by sidelong glimpses at football games and floating Snoopys on TV.

We all sit at tables with distant relatives and stragglers, breaking bread together.

That national sameness was very much a goal of the holiday's architects, who created it at an even more divisive moment. With the Civil War raging in 1863, President Abraham Lincoln and his secretary of state, William Seward, issued a proclamation on Oct. 3 calling for a national holiday to be observed on "the last Thursday of November."

That proclamation, a document of unusual literary grace, might do good service again in a nation that could use words of healing.

The proclamation is not generally listed among Lincoln's great achievements, and with good reason. Much of it was written by Seward. It may be surprising, on the face of it, to think that Lincoln needed a speechwriter. Most historians consider him the most talented wordsmith of all the presidents. But he and Seward had forged a close partnership, including acts of writing.

The brilliant peroration about our "better angels" at the end of Lincoln's first inaugural address stemmed from a thought Seward had first expressed. Their partnership was all the more impressive because these two career politicians had run hard against each other for the Republican nomination in 1860. That kind of cooperation between rivals, for a greater cause, is hard to find in 2019.

Seward had a reason for proposing a pointedly national holiday. As he and Lincoln knew well, Thanksgiving was celebrated in those days erratically around the country, with the dates set state by state, by governors. Seward had proclaimed four Thanksgivings of his own as governor of New York. There was no uniform practice.

Part of the problem was that the South distrusted a holiday tied to the early history of New England. Thanksgiving conjured images of the Pilgrims, a connection that was consciously promoted by a crusading journalist, Sarah Josepha Hale, who edited a popular women's magazine, Godey's Lady's Book. Hale had been advocating for a Thanksgiving holiday for decades (she also wrote "Mary Had a Little Lamb"). But she vexed Southern politicians with her anti-slavery writings, and many Southern governors, like Henry Wise of Virginia, refused to have anything to do with her precious holiday.

In the fall of 1863, Seward saw an opening. After two years of brutal fighting, the tide had turned, with Union victories the previous summer at Vicksburg and Gettysburg. That was reason enough to give thanks.

But what if the president issued a sweeping proclamation that gave thanks on behalf of the entire American people, including those who were at war against the United States? That would be creative statecraft, reminding Americans that they remained a single people.

Years later, Seward's son Frederick told the story through his father's memoirs, which he edited. One morning early in October, Seward went to Lincoln's room and found him working through a stack of papers. Seward joked that if the South was always going to accuse the federal government of "stealing away the rights of the States," Washington ought to at least steal something valuable.

Lincoln looked up, "with a quizzical expression," and asked, "Well, Governor, what do you want to steal now?" Seward answered: "The right to name Thanksgiving Day! We ought to have one national holiday, all over the country, instead of letting the Governors of States name half a dozen different days."

Lincoln entered "heartily" into the idea, adding that it was only a custom, and not a law, so a president had "as good a right to thank God as a Governor."

Seward had already written an outline of a proclamation, which "they read over together, and perfected." The word "perfected" suggests that Lincoln added a few of the phrases. It is difficult to know who wrote which line, but together they forged a document of enduring elegance.

In places, it has an Old Testament feeling, praising "our beneficent Father who dwelleth in the Heavens." But it also carries a message of charity, more in keeping with the New Testament. Even though huge armies were still clashing in the field, Seward and Lincoln never indulge in self-absorption or braggadocio. Instead, they write humbly of "the blessings of fruitful fields and healthful skies."

It is not all sweetness and light. Atypically for a government document, the proclamation expresses a sense of penitence, acknowledging "national perverseness and disobedience" — even "sins." Then it concludes with a dose of generosity to the disadvantaged, particularly "widows, orphans, mourners or sufferers."

And in perhaps the most important line, it celebrates one country, not two: "It has seemed to me fit and proper that they should be solemnly, reverently and gratefully acknowledged as with one heart and one voice by the whole American People."

It might be enough to end the story here and say simply that Seward and Lincoln had crafted a memorable statement of purpose, in the middle of a brutal war. But Lincoln still had great speeches left to give, and they show a debt to the Thanksgiving Proclamation of 1863.

When he went to Gettysburg just before Thanksgiving, Seward went with him. They were feeling thankful — in a spontaneous speech after arriving, Seward thanked God twice, once for the end of slavery and a second time "for the hope that this is the last fratricidal war which will fall upon this country."

Intriguingly, that evening Seward consulted closely with Lincoln on the speech the president was about to give. Was this another collaboration? Ordinarily, credit for the Gettysburg Address is given to Lincoln alone, and the available manuscripts are all in his hand. But there are signs that Seward and Lincoln were writing together again. In a recent study, the historian Martin P. Johnson found an anecdote from a Canadian official, who remembered that Lincoln asked to be excused, along with Seward, so that "we can get to work" on the speech.

One line of the Gettysburg Address, "it is altogether fitting and proper that we should do this," echoes the "fit and proper" line from the Thanksgiving Proclamation.

A year and a half later, Lincoln delivered his second inaugural address, which many scholars consider his finest effort. That, too, covered some of the ground Lincoln had tilled in the fall of 1863. He meditated on national sin, in a language uncharacteristic of presidents. But he went on to address penitence and forgiveness, and the particular duty to help the same "widows and orphans" he and Seward had mentioned in the Thanksgiving message. At the end of the earlier document, he asked that all Americans come together to "heal the wounds of the nation." As he concluded his second inaugural, he asked his fellow citizens to "bind up the nation's wounds."

The Civil War is never far distant; in troubling ways, it has resurfaced in recent months as an implied threat of a type of conflict that may reignite someday. How reassuring it is, in this context, to read the words of forgiveness that Lincoln and Seward wrote so carefully.

Even amid the worst of the fighting, with violence all around them, they saw a better day coming, when Americans would return to the same table, in the "full enjoyment of peace, harmony, tranquility and Union."

Ted Widmer is a distinguished lecturer at the Macaulay Honors College of the City University of New York. He edited the two-volume set "American Speeches" for the Library of America. His next book, "Lincoln on the Verge: Thirteen Days to Washington," comes out in the spring. He wrote this article for the Washington Post.