× Expand During the Civil War, 186,097 (7,122 officers, 178,975 enlisted) African-American men, comprising 163 units, served in the Union Army, and many more African Americans served in the Union Navy.

When Donald Trump, via tweet, instructed four American women of color who happen to be serving in Congress to “go back” to the countries they came from, he tapped into a painful history.

For many African Americans, being told to “go back” is about something bigger. It speaks to the desire of white America to bleach away the blood stains of its original sin: slavery.

In the decades after Emancipation, as the number of free black people increased, white men created the American Colonization Society (ACS) to address the “problem” that slavery had caused. The group began to send freed blacks to the colony on the African coast that would become Liberia in 1822; eventually thousands of former slaves inhabited the new land.

Fodei Batty, an assistant professor of political science at Quinnipiac University, says some scholars believe the ACS genuinely wished to abolish slavery and resettle blacks for their own welfare; but others see the effort as a politically expedient way to deal with a growing number of freed blacks in the upper South.

On August 14, 1862, President Abraham Lincoln met with black leaders of the day to advise them that the best way for blacks to help the Union effort was to leave.

President Abraham Lincoln advised black leaders that the best way for them to help the Union effort was to leave.

“You and we are different races,” Lincoln told the leaders. “We have between us a broader difference than exists between almost any other two races. Whether it is right or wrong I need not discuss, but this physical difference is a great disadvantage to us both.”

As Lincoln explained it, “your race suffer very greatly, many of them, by living among us, while ours suffers from your presence. In a word, we suffer on each side. If this is admitted, it affords a reason at least why we should be separated.”

Lincoln, at the beginning of his presidency, attempted numerous resettlement plans with ACS support, but none were successful. In 1862, Lincoln explored a plan to resettle blacks out of the United States.

Lincoln supported the plan of Bernard Kock to resettle blacks on an island off the coast of Haiti. On April 14, 1863, a ship carrying 453 former slaves departed from Virginia. But Kock proved to be an incapable leader, and the Haitian colony failed miserably. A handful of survivors ended up being returned to Virginia.

These attempts to deal with people of color by asking them to go away serves as a cautionary tale. Unity cannot be achieved by sending away those you perceive as the problem. What is required is a level of atonement that goes beyond simply removing the reminders of one’s own impurity.

No, America cannot remove the blood stain of its original sin. We also have more recent stains: voter suppression, mass incarceration, the lack of gun control, a health care system that doesn’t reach all.

These are the kind of issues the four congresswomen that Trump attacked are trying to address. Trump’s response is to suggest they remove themselves from a country he says they hate.

Rashida Tlaib, Alexandria Ocasio-Cortez, Ayanna Pressley and Ilhan Omar do not need to go back to anywhere. We need them to keep doing their important work.

And Trump? Maybe he’s the one who should be going back—to not being president.

This column was produced for the Progressive Media Project, which is run by The Progressive magazine, and distributed by Tribune News Service.