Between 1925 and the 1960s, in a tiny town called Tuam in western Ireland’s County Galway, thousands of “fallen women” and their “illegitimate” children passed through the Mother and Baby Home operated by the Congregation of the Sisters of Bon Secours. After a period of involuntary service and penance, many of the women who came to the home left to resume their lives, as The Post’s Terrence McCoy reported in 2014.

But some of the children did not leave. And what became of them remained a mystery into which few cared to inquire.

But after painstaking research, a local historian named Catherine Corless became convinced in 2014 that the infants and small children — perhaps 700 to 800 of them — died in the home and were buried without markers in mass graves beneath the property, perhaps in an underground structure such as a septic tank.

The story, which attracted worldwide publicity, was met with skepticism and even suggestions that it was a hoax. It wasn’t.

A commission established by the Irish government in response to her research and the ensuing controversy has reported finding “significant quantities of human remains” in 17 “underground chambers” inside a buried structure.

That structure, the commission said Friday, “appears to be related” to the treatment and containment of sewage and/or wastewater, though it was uncertain whether the structure was ever used for that purpose.

There is no uncertainty about the remains.

A small number of them were recovered for analysis, the commission reported. “These remains,” it said, “involved a number of individuals with age-at-death ranges” from approximately 35 fetal weeks to 2-to-3 years.

“Radiocarbon dating of the samples recovered suggest that the remains date from the time frame relevant to the operation of the Mother and Baby Home,” the commission said. “A number of the samples are likely to date from the 1950s.”

Further tests are being conducted.

The commission said it was “shocked” by the discovery and “is continuing its investigation into who was responsible for the disposal of human remains in this way.”

The testing and excavation found another structure as well, which the commission said appeared to be “a large sewage containment system or septic tank that had been decommissioned and filled with rubble and debris and then covered with top soil.” The report did not say whether researchers had yet looked for remains in that structure.

“This is very sad and disturbing news,” Katherine Zappone, Ireland’s minister for children and youth affairs, said in a statement. “It was not unexpected, as there were claims about human remains on the site over the last number of years.”

But previously the claims amounted to mere rumors, Zappone said. “Now we have confirmation that the remains are there, and that they date back to the time of the Mother and Baby Home,” she said.

“Today is about remembering and respecting the dignity of the children who lived their short lives in this Home,” Zappone added. “We will honour their memory and make sure that we take the right actions now to treat their remains appropriately.”

In a statement published in the Irish Times, the Bon Secours sisters said they were “fully committed to the work of the commission regarding the mother and baby home in Tuam. … On the closing of the home in 1961, all the records for the home were returned to Galway County Council, who are the owners and occupiers of the lands of the home. We can therefore make no comment on today’s announcement, other than to confirm our continued cooperation with and support for the work of the commission in seeking the truth about the home.”

Corless’s original theory and now its confirmation “provide a glimpse into a particularly dark time for unmarried pregnant women in Ireland, where societal and religious mores stigmatized them,” McCoy wrote in 2014 for The Post.

Without means to support themselves, women by the hundreds wound up at the Home, Corless told The Post in 2014. “Families would be afraid of neighbors finding out, because to get pregnant out of marriage was the worst thing on Earth. It was the worst crime a woman could commit, even though a lot of the time it had been because of a rape.”

The government’s placement of mothers in institutions such as the Tuam home was a form of social welfare outsourcing, accompanied by payments to the homes, albeit small ones.

Corless’s research found that infant mortality at the home in Tuam was particularly high. Records for that home show that babies died at the rate of two per week from malnutrition and neglect, and from diseases such as measles and gastroenteritis, Corless told the Post in 2014.

Her interest in a subject others preferred to forget began when she was doing research for an annual local historical journal. She heard about a graveyard near what had been the Tuam home and wondered how many children might be buried there. In addition to looking at records of deaths at the home, Corless found that several boys had stumbled across a cracked piece of concrete “filled to the brim with human skulls and bones,” she told The Post in 2014. “They said even to this day they still have nightmares of finding the bodies.”

In the wake of the commission’s report Friday, Corless told the Irish Times that it was “an enormous relief to have the truth come out about what I knew. I can only imagine what the survivors of those who died there must feel, and those who had family connections to the home. The Church and State owes them all an apology,” she said.

The commission is already investigating how unmarried mothers and their babies were treated between 1922 and 1998 at 18 religious institutions used by the state.

“This could have gone either way,” Corless told the Irish Mirror.

“It could have been covered up as it was in the 1970s when this investigation should have taken place,” she said. “The county council knew at the time that there were remains there, the guards knew it, the religious [orders] knew it and it was just all nicely covered in and forgotten about.

“When I started this research,” she told the Mirror, “I was asked, ‘What are you doing? It’s a long time ago. If there’s bodies there just leave them.’”