It was a blazing hot July afternoon, and the condemned were led in irons from the Washington penitentiary about 1 p.m.

They passed the pre-dug graves and the stack of gun crates that would serve as their coffins and climbed the steps of the wooden gallows that had been built overnight.

Shuffling onto the crowded platform, they were hooded and bound with strips of white cloth. Nooses were slipped over their heads.

The three men and one woman had been found guilty of conspiracy in the assassination of “the late president, Abraham Lincoln,” as official documents put it.

A century and a half ago this month — on July 7, 1865 — one of the last grim scenes in the tragedy of the Civil War was played out — and caught on camera — at what is now Fort McNair, in Southwest Washington.

Ropes are adjusted for hanging the conspirators in President Lincoln’s assassination on the gallows on July 7, 1865, at Fort McNair in Washington. (Alexander Gardner/Library of Congress)

Mary E. Surratt — the first woman to be executed by the federal government — Lewis Powell, George Atzerodt and David Herold had been convicted by a military tribunal of conspiring with John Wilkes Booth in the murder of Lincoln.

Booth had been killed 10 weeks earlier while trying to escape, after shooting Lincoln in Ford’s Theatre on April 14.

All the condemned were local Southern sympathizers implicated in the plans, first to kidnap Lincoln and later to kill him, Vice President Andrew Johnson and Secretary of State William Seward.

Seward survived a brutal knife attack by Powell the night Lincoln was shot. Johnson escaped harm when Atzerodt lost his nerve and failed to execute his part of the operation.

Herold had helped Booth escape and was “the getaway guy,” as one expert put it.

And by most accounts, Surratt knew of the plot and abetted the plotters from her boarding house on H Street NW.

The four were lined up — their arms handcuffed, their feet shackled — as an officer read the execution order and the photographer, Alexander Gardner, aimed two cameras from about 100 feet away.

Then Gardner and his team recorded “perhaps the most striking sequence of historical photographs ever made,” according to historians James L. Swanson and Daniel R. Weinberg.

Frame by frame, the photographers captured the preliminaries and hanging in 10 stark photographs, said Barry M. Cauchon, a New York scholar who has studied the execution.

The hanging was one of the few acts of official retribution to come after the war, experts said, but it symbolized the North’s collective rage over the rebellion and the assassination.

“Every loyal American feels that the death of Mr. Lincoln is not only a national, but a personal, bereavement,” Washington’s Daily Morning Chronicle wrote. “And everyone is controlled, in some measure, by revengeful feeling.”

But when Gardner tried to sell the images later, they didn’t do well, said John Elliott, another student of the execution. “Maybe the country didn’t have enough stomach for it anymore,” he said.

The first Gardner image shows the gallows beforehand, empty except for four chairs. Others then show the scaffold crowded with the condemned, officials and clergy, huddled under umbrellas to escape the sun.

In yet another picture, officials can be seen adjusting the nooses around the necks of the four.

Surratt wore a dark veil and a floor-length black alpaca dress buttoned in the front. A Catholic priest holding a cross ministered to her as she sat in a chair while the warrants were read.

None of the condemned appeared to be wearing shoes.

As they stood and awaited the release of the two “drop” sections of the platform, Surratt was supported by two soldiers who kept her from toppling prematurely. “Don’t let me fall,” she said.

Atzerodt said, “Goodbye, gentlemen. . . . May we all meet in the other world! God help me now!” according to the Washington Evening Star’s account.

At 1:26 p.m., the supports were knocked out.

“The drops fell with a heavy slam, and the four bodies hung suspended,” the newspaper reported.

In one of Gardner’s last shots, the two soldiers supporting Surratt stand with their arms extended, having just let her go.

“The last act in the tragedy of the 19th century is ended,” the Star pronounced. “And the curtain dropped forever upon the lives of four of its actors. . . . The wretched criminals have been hurried into eternity, and tonight will be hidden in despised graves, loaded with the execrations of mankind.”

The awful event

Paul M. Severance stood in the quiet third-floor room of Grant Hall on the grounds of Fort McNair last month, decked out in the gold buttons and sweltering blue uniform of a Union general.

There was some filming equipment in a corner, left over from a weekend reenactment of the trial, and Severance bustled around, preparing for the lecture he was about to give.

Today, Grant Hall is home to the Defense Department’s Africa Center for Strategic Studies.

In 1865, it was a wing of the old and largely vacant federal penitentiary that held the Lincoln conspirators. And the room where Severance stood served as the courtroom where the trial was held.

Much of the room is not original, although some of the floorboards are, but it has been restored and refurnished to the way it looked in 1865. It’s open to the public on a limited basis.

It’s also said to be haunted by Surratt’s ghost, according to Severance, a professor of military science at the National Defense University. Lights inexplicably go on and off, and the disembodied sound of hammering, as if from gallows building, has been heard at night, he said.

There, where the Capitol can be seen from one of the windows, eight conspirators were found guilty, and the four were sentenced to death. The others got lesser sentences.

The trial, which opened May 9, was a national sensation, Severance said.

The defendants were accused of “maliciously, unlawfully and traitorously . . . conspiring . . . (to murder) Abraham Lincoln, then president of the United States,” the official charges stated.

The hot, stuffy courtroom was crammed with reporters, illustrators and spectators eager to glimpse the conspirators, especially the veiled Surratt, and the handsome Powell, a 21-year-old former Confederate soldier.

Hundreds of witnesses testified, including the top Union general, Ulysses S. Grant; Maj. Henry Rathbone, who was knifed by Booth seconds after Lincoln was shot; and Sgt. Boston Corbett, who fatally wounded Booth on April 26.

The details of the assassination were given, and links between Booth and the defendants were established.

The original plot had been to abduct Lincoln and use him as a hostage to gain the release of Confederate prisoners of war, said Severance, a retired Army colonel.

But as the rebel cause withered, Booth decided that something else had to be done, something he called “decisive and great . . . which the world would remember for all time,” according to a new biography of Booth by historian Terry Alford.

Defense lawyers argued that the trial should have been in a civilian court, and that many of the defendants were only in on the kidnapping plot, not the assassination.

The tribunal was unmoved.

It began deliberating June 29 and presented its verdicts to President Johnson on July 5, according to Swanson and Weinberg’s book, “Lincoln’s Assassins.” Johnson approved.

On July 6, Powell, Surratt, Atzerodt and Herold were informed that they were to be hanged the next day.

Two generals went to each cell — first Powell’s, then Atzerodt’s, Herold’s and Surratt’s, according to the account in the Star newspaper.

Powell, who used the alias Payne, seemed resigned. Atzerodt grew pale, and his hands began to shake. Herold admitted helping Booth escape and said he had always been an ardent supporter of the South.

Surratt was stunned and burst into “a violent paroxysm of grief,” the newspaper said. Last-minute appeals to a civilian court and the White House were made for her. They all came to nothing.

Surratt’s daughter, Anna, went to the executive mansion to beg for an interview with Johnson.

Told that he would see no visitors, she collapsed on a staircase, “sobbing aloud in the greatest anguish, protesting her mother’s innocence . . . (declaring) her mother was too good and kind to be guilty of the enormous crime,” the newspaper reported.

“The scene was heart rending, and many of those who witnessed it . . . were moved to tears,” the Star recounted.

The next morning, the operation of the freshly built gallows designed to hang four people simultaneously was tested.

Artillery shells weighing 100 pounds were placed on the drop sections, and the supports were knocked away, the newspaper reported. Some adjustments were required.

Meanwhile, the city was crowded with visitors, hoping to witness or just be in town for the execution. Admission was strictly limited. About 3,000 spectators, most of them soldiers, looked on from the ground, windows and rooftops.

The condemned emerged from the prison, accompanied by members of the clergy, and filed up to the scaffold platform. The death warrants were read. The four stood. The nooses were affixed.

The temperature was in the mid-90s.

The executioner, Capt. Christian Rath, who had come to admire Powell’s pluck, said in an interview many years later that he had whispered to Powell, “I want you to die quick.”

“You know best, captain,” Rath said Powell replied.

Rath told his interviewer that he was sure Surratt would be spared. And when his superior, Gen. Winfield Scott Hancock, ordered him to proceed, Rath asked, “Her, too?”

“Yes,” Hancock said. “She cannot be saved.”

Rath gave the signal — three claps of the hand, according to the National Intelligencer. “As one, the four bodies shot downward,” he recalled.

They were lowered after about 20 minutes. The shackles and irons were removed, but not the execution hoods.

Each body was placed in a coffin, along with a glass bottle holding a piece of paper bearing the conspirator’s name and the nature of the crime. The four were buried in the graves beside the gallows and over the years returned to their families.

The awful event was finished, the National Intelligencer wrote, as if speaking of the upheaval of the past four years.

“God grant that our country may never again witness such another one.”

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