By the time the sun set on the evening of Sept. 11, 2001, a wounded, grieving nation wept. The full magnitude of the loss of life wasn’t yet known, but this much was certain: The United States had suffered an unprecedented attack on our own soil, with civilians, service members, and political leaders alike all targeted by a foreign enemy.

Soon, many Americans began demanding retribution — or, as the Philadelphia Daily News put it the day after the attacks, “Blood for blood.”

“Revenge,” began a Daily News editorial on Sept. 12. “Hold on to that thought. Go to bed thinking it. Wake up chanting it. Because nothing less than revenge is called for today.”

The Daily News editorial board, which has since merged with The Inquirer’s, clearly tapped into a common sentiment. The opinion and letters pages of both newspapers during the days and weeks after the attacks illustrate a pervasive sense of vengeance — “Let us flex our muscles,” “give war a chance,” “punishment without mercy,” “I don’t know why we just don’t retaliate now.”

If there was ever a time for collective outrage, it was certainly after the deaths of 2,753 people in the Twin Towers, of 184 people at the Pentagon, and of the 40 passengers and crew members of United Airlines Flight 93, who sacrificed their lives to avert another attack.

But 20 years later, there are lessons to be learned about where an open-ended call for blood can lead — and about the role of the military, politicians, and the media in creating the conditions for a forever war.

With images of last month’s chaotic withdrawal from Afghanistan top of mind, it’s critical for every institution — including this board — to reflect on its own role in shaping the events of the last 20 years.

Both The Inquirer and Daily News editorial boards supported the war in Afghanistan — as did eight out of ten Americans at the time and all but one member of Congress.

After American forces occupied Kabul in November 2001, an Inquirer editorial read: “The taking of Kabul presents new challenges — but the aims remain the same.” A forever war was brewing.

The temperature of editorials was lower on Iraq, but the conclusion was the same: approval of war.

We have the privilege of hindsight that our colleagues in the past didn’t have. We now know that the Bush administration misled the country about weapons of mass destruction in Iraq. We also know that the Pentagon misled both the American public and the White House about the progress that it said was being made in Afghanistan.

In 2008, members of The Inquirer’s board reflected on their position about the Iraq War, writing that the White House claims that Saddam Hussein had weapons of mass destruction persuaded them that the “invasion was the right thing to do” but that in retrospect “it looks incredibly foolish to have believed” those claims.

Those beliefs also shaped policy and changed lives. The experience of Muslims, Sikhs, and people of Middle Eastern origin in America has never been the same after the attacks and the American immigration system became more exclusionary and enforcement-driven.

It is not lost on this board that many institutions, including newspapers, have a role in that.

Surely, there are steps that can provide a measure of justice for victims of Sept. 11 that don’t require a declaration of war — and that officials have not yet taken. Dennis Baxter, the brother of Jasper Baxter — a Philadelphian who was killed in the South Tower — said that he and his family have not stopped seeking answers about the potential extent of the Saudi government’s role in the attacks. “They’re still trying to figure out who to really blame,” Baxter told this board recently, alluding to official resistance to releasing additional details about those connections.

Perhaps one lesson from 9/11 may be a collective recalibration between our competing impulses for justice and vengeance — and the importance of not conflating demands for blood with the pursuit of full accountability.

“Even after 20 years, you still feel the pain,” Baxter said. “Who knows what the next 20 years will bring?”