Beyond the validity of the suit, something of much larger impact is at play: the need to nourish a debate on the true history of a war the United States has conveniently forgotten or camouflaged and which now, more than ever, should be honestly remembered as it was. It’s a matter of an enormous crime, which leads to a question: How much of the historic prosperity of the United States of America stems from the development of territories originally inhabited by Mexicans and ripped away from Mexico through an invasion and a war of territorial conquest?

Because it was exactly that. Many American soldiers were aware of it, reading William Prescott’s “History of the Conquest of Mexico” — a recounting of Hernán Cortés’s expedition to conquer the Aztec Empire — as they advanced across Mexican territory. Many important figures of the epoch, with shame and regret, recognized its nature. That “most outrageous war” (John Quincy Adams wrote) had been “actuated by a spirit of rapacity and an inordinate desire for territorial aggrandizement” (Henry Clay), and began with a premeditated attack by President James Polk, thanks to which “a band of murderers and demons from hell” were “permitted to kill men, women and children” (Abraham Lincoln).

After the naval bombardment of the civilian population of Veracruz, Robert E. Lee wrote to his wife, “My heart bleeds for the inhabitants.” In his memoirs, Ulysses S. Grant lamented that he had not had “the moral courage to resign” from what, as a young officer, he had described as “the most wicked war.” For a number of other politicians and thinkers, including Henry David Thoreau, the war contradicted the democratic and republican values on which the country had been founded and was opposed to basic Christian ethics.

Mr. Cárdenas’s initiative may have little chance of succeeding legally, but its public impact could be considerable at a time when Mexico is being attacked unjustly by President Trump.

The United States owes Mexico and itself an honest reconsideration of its first imperial war, not only in its schools and universities but also in its museums and books. Hollywood and Broadway, which have always played an important role in shaping the American historical consciousness, should take up the issue.

Films, documentaries and memorable TV series have helped to modify the memory of two original sins, slavery and racism against African-Americans, and, with somewhat lesser attention perhaps, the racist slaughter and repression of the American Indians. A third sin should be added to these: the aggression against Mexico and the plundering of its territory.