Last week, a mash-up video of dozens of local news anchors denouncing the spread of “biased and false news” and professing a commitment to being “fair, balanced, and factual” went viral. The clip revealed that these Sinclair Broadcast Group journalists were reciting from an identical script.

Sinclair — the nation’s largest owner of local television stations and a longtime vehicle for “outlandish propaganda” with a “far-right slant” — seems to be operating out of the modern conservative playbook. The media conglomerate parrots the language of Fox News and President Trump, each adept at camouflaging hyperpartisan positions and outright lies with emphatic claims of objectivity and stern accusations of bias.

But this is nothing new. In fact, Sinclair is building on a time-honored American tradition that dates back to the 19th century, when defeated Confederates and their offspring used allegations of “bias” to rewrite the history of the Civil War.

According to the Lost Cause — a false narrative that posited the moral sanctity of the Confederacy and the Old South — southern boys did not march off to war to protect slavery. Instead, they fought in defense of virtuous ideals, such as states’ rights, low tariffs and constitutional liberty. What’s more, this narrative cast the institution of slavery as benevolent and civilizing. Manipulating history in the service of white supremacy, the Lost Cause ultimately reinforced racial hierarchy in the postwar South.

Charges of bias were the stock in trade of Lost Cause prophets, who took umbrage at what they insisted were flawed accounts of the war being produced in the North. A South Carolina veterans organization founded in 1869 announced that it was dedicated to “collecting and preserving facts for a full and impartial history” of the war. Four years later, the president of the newly created Southern Historical Society lamented that “the country has been flooded with partisan histories,” asserting that it was “high time steps were taken to record the incidents of those eventful years as they occurred.”

This campaign intensified at the turn of the 20th century, when members of the newly formed United Confederate Veterans (UCV) and United Daughters of the Confederacy (UDC) launched a movement to purge “prejudicial” history textbooks from Southern classrooms. Concerned that the vast majority of textbook authors and publishers were situated outside the South, Lost Cause proponents viewed it as their sacred duty to ensure that Southern boys and girls were not exposed to what one UCV member called “long-legged Yankee lies.”

The UCV formed a historical committee to choose a “proper and truthful history of the United States, to be used in both public and private schools of the South” and to “put the seal of [its] condemnation upon such as are not truthful histories.” Members of the UDC’s historical committee published lists of textbooks they deemed objectionable in newspapers and lobbied school boards and principals to substitute UDC-approved alternatives. “No better work can be done by the women of any community,” maintained a Charleston, S.C., UDC leader, “than to preserve the facts of history pure and free from prejudice. … Truth, at any cost, should be their watchword.”

This textbook crusade was wildly successful, convincing school districts throughout the South and beyond to adopt approved works. “We do not fear the bookmaker now,” stated the UCV historical committee in 1910. “Printing presses all over the Southland — and all over the Northland — are sending forth by the thousands volumes which tell the true character of that brief but heroic struggle. The influence and wealth of the South forbid longer the perversion of truth and falsification of history.”

Yet these Confederate memory groups were anything but impartial truth-tellers. Instead, they collected and promoted narratives of the war that ran roughshod over the historical record.

Lost Cause defenders taught generations of Americans that the Confederates did not fight for slavery. And the textbooks they endorsed, such as Susan Pendleton Lee’s “Advanced School History of the United States,” whitewashed the institution. “The kindest and most affectionate relations existed between the slaves and their owners,” Lee wrote. Under slavery’s influence, “hundreds of thousands of African savages [were] civilized and Christianized.”

In South Carolina, former Confederates even had the gall to argue that they — rather than Abraham Lincoln, the Republican Party, the Union army and the enslaved themselves — had been the true anti-slavery force in the state.

The Lost Cause was not the product of an honest disagreement over how to interpret historical facts but a willful distortion of them. It was actual “fake news”— or to be more specific, fake history — and its grip remains firm, distorting Americans’ understanding of our greatest conflict.

Modern-day supporters of Confederate monuments continue to insist that such memorials have nothing to do with the white Southern defense of slavery. Meanwhile, 41 percent of Americans do not believe that slavery precipitated the Civil War. According to a troubling new report, only 8 percent of high school seniors correctly identify the institution as the war’s central cause.

A century ago, Lost Cause champions routinely maintained that their histories of the war were unbiased. It was a shrewd rhetorical strategy, a preemptive strike that discouraged potential challenges to their claims. The tactic not only played to a growing faith in scientific objectivity; it also appealed to white northerners’ desire for sectional reconciliation. And it spoke to the present as well as the past, bolstering white supremacy — the backbone of both the Confederacy and the Jim Crow regime that white southerners were imposing in the early 20th century.

No good journalist or scholar would dispute that striving for objectivity is a noble, if ultimately quixotic, goal. But strident proclamations that stories are unbiased do not make them so. Indeed, in today’s conservative media universe, shaped by the “fair and balanced” Fox News, such declarations bespeak quite the opposite. Sinclair Broadcast Group, like Lost Causers, doth protest too much.

As with Lost Causers proclaiming the fairness of textbooks, Sinclair’s new “fair, balanced, and factual” pitch — an obvious nod to Fox — is an attempt to run down the competition and signal to viewers that they can trust Sinclair for a conservative slant. That’s why the company has found such an enthusiastic fan in the person of President Trump, who, unsurprisingly, tweeted his approval. The message should be clear: Viewer beware.