The Trial of Red Jacket, painted in 1869 by John Mix Stanley was almost destroyed in the Smithsonian Institution's fire of 1865. Red Jacket (1758-1830) was a famous leader of the Seneca tribe of the Iroquois Nation. (John Mix Stanley/Smithsonian American Art Museum)

The weather had been unusually cold that winter, and the two workers rearranging the paintings in the unheated gallery at the Smithsonian Institution had installed a temporary stove to keep warm.

The gallery was a fascinating place, with tall, arched windows. Lining the walls were hundreds of majestic portraits of Native Americans: Cherokee statesmen, Potawatomi warriors, Osage chieftains.

Pawnee, Comanche and Ojibwa figures, some painted 40 years earlier, were crammed floor to ceiling, as the workers ran a stovepipe to what they thought was an exhaust flue.

A few days later, on Jan. 24, 1865, the red sandstone Smithsonian erupted in flames, and a large portion of the structure was destroyed along with documents, artifacts and almost the entire collection of Indian paintings.

Crowds gathered on the frigid expanse of the Mall as a roof collapsed, smoke and flames poured from the building, and volunteers threw books out the windows to save them.

Burning of the Smithsonian Institute at Washington on Jan. 24, 1865, sketched by Philip Wharton, is shown in this wood engraving from 1865. (Library of Congress)

The workers had been wrong: They had run the pipe not to an exhaust flue, but into a hole that emptied behind the wall.

It was the most destructive fire in Smithsonian history — 150 years ago Saturday — one official said. And it erased a trove of original pre-Civil War Indian imagery, along with much of the work of two prominent portrait painters.

It was a “tremendous loss,” said Pamela M. Henson, a historian with the Institutional History Division at the Smithsonian’s archives. “It was pretty tragic across the board.”

The fire destroyed many of the personal papers of James Smithson, the British scientist whose bequest of $500,000 had launched the institution in 1846, as well as records, documents and scientific instruments.

“It’s amazing that it didn’t completely burn to the ground,” Henson said.

A handful of the Indian paintings were saved by frantic employees who pulled them off the walls as part of the second-floor gallery ceiling collapsed.

But more than 250 were lost, according to Smithsonian records and scholars.

Also lost was much of the original work of the well-known Indian portrait painters Charles Bird King and John Mix Stanley.

Stanley, then 49, was an artist and explorer who had roamed the country, joined expeditions and painted Native Americans in settings where they lived in the 1840s, from Arkansas to Washington state.

He often maneuvered around the violence between Indians and settlers to do his work. At least 150 of his Indian paintings had been at the Smithsonian since 1852, scholars believe.

King, who lived in Washington and died in 1862, had been hired by the government to paint portraits of the scores of Indian leaders who came to the capital to negotiate treaties, settle grievances or meet the president.

King’s 139 paintings had joined Stanley’s at the Smithsonian in 1858.

Together, they made up “the most valuable collection in existence of illustrations of the features, costumes and habits” of Native Americans, wrote the Smithsonian’s first secretary, Joseph Henry, according to a study of King’s work by Herman J. Viola.

King’s “paintings were extremely important,” Viola said in a recent telephone interview.

He was probably the first white artist to portray an Indian wearing a war headdress — the Pawnee leader Petalesharro, or Generous Chief, Viola said.

King was also first to paint a Plains Indian woman, Hayne Hudjihini, or Eagle of Delight, he said.

King did, however, make copies for various people. The White House has two.

“So those are the ones that have surfaced,” Viola said.

But originals, such as those of Tshusick, an Ojibwa woman clad in a pink jacket and holding a pink rose; Amiskquew, a Menominee warrior wearing green feathers and a green robe; and Pashepahaw, a Sauk chief with black hair and black bandanna, were apparently lost in the fire.

“There’s no way to put a price tag on it,” Viola said. “It was an enormous loss . . . [and] one of those unknown stories.”

Many of King’s paintings had been lithographed before the fire, and the lithographs survive.

As for Stanley, an 1852 catalogue of his work at the Smithsonian lists about 150 paintings, with descriptions, the majority of them Indian portraits.

“The collection . . . comprises accurate portraits painted from life of forty-three different tribes of Indians, obtained at the cost, hazard, and inconvenience of a ten years’ tour through the South-western Prairies, New Mexico, California and Oregon,” Stanley wrote in the preface.

They included an 1842 portrait of Cowockcoochee, or Wildcat, a Seminole chief and formidable foe of U.S. forces; an 1843 painting of the Ottawa warrior Shabanee; and an 1843 image of the Shawnee leader, Quahgommee.

There was a portrait of the burly Osage chief Techongtasaba, or Black Dog; a painting of the Iowa chief Wohumpa, who insisted on being portrayed shaking hands with Stanley; and a portrait of a Creek woman, Semiwocca, dressed in calico.

There were scores of other portraits — of Chippewa, Delaware, Chinook, Chickasaw, Nez Perce — almost all likely lost in the fire.

At least one of Stanley’s originals escaped the flames, according to the Smithsonian: his dramatic “The Trial of Red Jacket,” in which the famous Seneca orator is shown defending himself against a charge of witchcraft.

Five other works were in a different part of the building and survived, according to a 1924 Smithsonian report. All six are now in the Smithsonian American Art Museum.

As for the others, the report said, “The destruction of the collection . . . caused an irreparable loss . . . which will be more fully appreciated in the future when the events depicted and the individuals shown will belong to the vague past.”

During the 1820s and ’30s, with the frontier pressing westward and the government moving Indians out of the way, dozens of Indian delegations came to Washington to appeal or negotiate, Viola wrote in his book on King’s work.

Eighteen treaties were signed in Washington between 1821 and 1838, he wrote.

So many Indian leaders came that King could not paint them all, although he did portray figures from 20 different tribes in his studio at 12th and F streets NW.

No artist of the time painted members of more tribes, except for George Catlin, who painted later and was inspired by King’s lithographs, Viola said. Hundreds of Catlin’s famous paintings also went to the Smithsonian, but not until 1879.

As the Indian delegations to Washington visited the White House and Congress and had their portraits painted, the visits took a toll on some of the visitors.

The Choctaw leader Pushmataha, who was painted by King, caught a cold, collapsed and died in December 1824. (He is buried in Congressional Cemetery.)

The Creek leader Opothle Yoholo, also painted by King, attempted suicide in despair over treaty negotiations.

And the young Oto woman Hayne Hudjihini, whom King painted wearing elegant earrings and braids, died of measles weeks after returning home from Washington, Viola recounted in his book.

Stanley worried about the fate of his portrait subjects.

In 1852, he wrote: “A few generations hence our descendants will have nothing except . . . memorials, to remind them of the . . . existence of a race, which had made perhaps a more gallant and prolonged defense of their independence, than any recorded.”