Some call it “The Great Resignation,” others a “strike wave.” It’s hard to know what to make of the enormous churn now taking place in the American workplace. There have been a few high-profile strikes, but these are overshadowed by the 4.4 million workers who quit their jobs in September, the latest month for which we have data. That’s the highest number in more than 20 years. Restaurants and stores are understaffed, while employers put out help-wanted posters and jack up wages.

Economists and historians are puzzled. What’s the best analogy? World War II, when the war industries sucked labor off the farm and out of the kitchen? Or maybe the boom of the late 1990s, when unemployment sank below 4 percent and neither the big box stores nor Silicon Valley could stop workers from jumping to a better job?

W.E.B. Du Bois may have the answer. He was the greatest scholar of African American life in our nation’s history, and in 1935, Du Bois published an epochal study, “Black Reconstruction in America,” that revolutionized our understanding of the Civil War and the effort to build a truly democratic and racially inclusive South in the years afterward. Narrating an era of unprecedented social turmoil, his book sheds a penetrating light on our own moment of economic upheaval and the power so many workers, of all races and ethnicities, have won to reshape their lives.

Chapter Four of Du Bois’s book, titled “The General Strike,” told the story of how hundreds of thousands of enslaved people fled the plantations and flocked to those parts of the South dominated by the Union army. “There was no plan to this exodus,” wrote Du Bois, “no Moses to lead it.” In Virginia, along the Mississippi River and throughout the sea islands of Georgia, thousands fled to the forts, ports and encampments of the Union army.

Declared “contraband” of war, they were employed and paid wages according to the gendered norms prevalent in the North: the men building fortifications and hauling military supplies, the women cooking, washing and mending clothes for soldiers along with the multitude of others fleeing Southern plantations. By depriving the Confederates of their labor power, argued Du Bois, Black Americans crippled the Southern economy and struck a decisive blow for their own emancipation.

Union victory in 1865 greatly enlarged the strike movement. Now millions of formerly enslaved African Americans abandoned the plantations and exercised newly won freedoms: to travel, to reunite families, to attend church services and put their children in schools. Some Whites called this an “aimless migration,” but many who left Virginia and the Carolinas for Texas and Louisiana found higher wages there. In cities all across the South, formerly enslaved people saw that the presence of the Army and the new Freedmen’s Bureau, a kind of federal welfare agency for the formerly enslaved, offered some support and protection.