“This history (of Thanksgiving) teaches us that the American instinct has never been to seek isolation in opposite corners; it is to find strength in our common creed and forge unity from our great diversity. On that very first thanksgiving celebration, these same ideals brought together people of different backgrounds and beliefs, and every year since, with enduring confidence in the power of faith, love, gratitude, and optimism, this force of unity has sustained us as a people. It has guided us through times of great challenge and change and allowed us to see ourselves in those who come to our shores in search of a safer, better future for themselves and their families.” — President Obama, 2016

While Thanksgiving is clearly a celebration of gratitude for a bountiful harvest, its origin and history in the United States tell an unexpected tale of unity that is particularly relevant in these divisive times.

While the early history of the United States is rife with atrocities committed against Native Americans, the “first Thanksgiving” — a three-day feast in 1621 in what is now Plymouth, Mass. — was a peaceful moment of fellowship between the English settlers and the Wampanoag among whom they lived.

In one of two existing accounts of that feast, Edward Winslow wrote of the “many of the Indians coming amongst us, and amongst the rest of their greatest king Massasoit, with some ninety men, whom for three days we entertained and feasted.” Another English settler who arrived shortly after that first feast, William Hilton, described in a letter to his cousin “the Indians round about us” as “peaceable and friendly.”

Over the next century and a half, Thanksgiving was celebrated at different times by the separate colonies. The Continental Congress issued the first National Proclamation of Thanksgiving in 1777:  “It is therefore recommended to the legislative or executive Powers of these United States to set apart Thursday, the eighteenth Day of December next, for Solemn Thanksgiving and Praise …” 

Over the year, various days of Thanksgiving would be proclaimed by Congress and presidents, as well as governors, but an annual, recurring, nationwide holiday would not be proclaimed until 1863, in the middle of the Civil War.

President Abraham Lincoln was prompted by the writings of magazine editor Sarah Josepha Hale, who wrote to him on Sept. 28, 1863: “You may have observed that, for some years past, there has been an increasing interest felt in our land to have the Thanksgiving held on the same day, in all the States; it now needs National recognition and authoritive fixation, only, to become permanently, an American custom and institution.”

President Lincoln’s proclamation was more than a declaration of a holiday. It was also a heartfelt plea for an end to the war and a reunification of the nation. He invited his fellow citizens not only to set apart the last Tuesday of November “as a day of Thanksgiving and Praise to our beneficent Father who dwelleth in the Heavens,” but also to “fervently implore the interposition of the Almighty Hand to heal the wounds of the nation and to restore it as soon as may be consistent with the Divine purposes to the full enjoyment of peace, harmony, tranquility and Union.”

In an effort to lengthen the Christmas shopping season and stimulate the economy in the midst of the Depression, President Franklin D. Roosevelt briefly changed the date of the holiday to the next-to-last Thursday. But the move was considered an affront to President Lincoln’s memory and triggered partisan outrage.

Nov. 30, 1939, was considered “Republican Thanksgiving” and Nov. 23 as “Democratic Thanksgiving” or “Franksgiving.” The experiment appeared to fail, with no measurable boost to the 1939 and 1940 Christmas shopping seasons.

On Dec. 26, 1941, Congress passed a law making Thanksgiving the fourth Thursday of November, where it has remained — a bipartisan celebration — ever since.

It’s instructive that we find the pivotal moments in the development of modern Thanksgiving in the United States at the time of the Civil War and the Great Depression.

We are once again facing a crisis of division. As we give thanks for the blessings that have been visited upon us, let us also remember to pray for healing and a reunification of our nation.

The writer is president and CEO of the National Urban League.