A large percentage of Butte’s Irish immigrants came from this part of Ireland, and for their descendants, Riobard O’Dwyer was a godsend.

O’Dwyer, genealogist extraordinaire, died early Wednesday in Eyeries.

Before such genealogical search engines as ancestry.com or the easy accessibility of familysearch.org, there were O’Dwyer’s books, a total of four volumes, aptly titled “Who Were My Ancestors?” They were a treasure trove of information.

“He chronicled the immigration of the Beara Peninsula so wonderfully,” said Ellen Crain, director of the Butte-Silver Bow Archives.

Within the pages of these books, those looking to expand their family tree could find detailed information on their ancestors — when they were born, who their parents and siblings were, who they married, if they married, when or if they made their way to Butte, and sometimes, when they returned to their homeland.

“The books became a touchstone to our family stories and cultural history,” said Crain.

When news of O’Dwyer’s death spread, the accolades started coming in.

“What an amazing help he was to all the Beara descendants … May he rest in peace,” one woman wrote.

Another sent this message – “He gathered a wealth of information and many generations to come will be forever grateful.”

O’Dwyer made a trip to Butte in 1994, a visit he considered long overdue. He was not disappointed.

Butte felt like home to the long-time teacher.

“Except for not having the sea rolling up to its shores,” O’Dwyer said in a 1994 interview, “the whole atmosphere here could lead one to imagine that a big part of the Beara Peninsula was lifted up off the southwest of Ireland, set down in the middle of the Rocky Mountains and renamed Butte, Montana.”

Brothers Jim and Jerry Sullivan were O’Dwyer’s second cousins and both were floored with not only how much O’Dwyer knew about their family tree, but how much knowledge he had on Butte’s Irish immigrant population.

Jerry visited his Eyeries cousin several times. “He was always gracious and hospitable,” he said.

O’Dwyer received lots of visitors in Eyeries, looking for help as they searched for information on their ancestors. Many of these visitors were from Butte, and O’Dwyer was always happy to oblige.

The Sullivan brothers were amazed at O’Dwyer’s work ethic, both as a teacher and as an historian.

“That anyone would have the interest, intelligence and energy to do the work he did is amazing,” said Jerry.

“He was also a damn good accordion player,” said Jim.

Jim recalled one particular visit he made to Ireland and stopping by to see O’Dwyer.

“He was always the consummate host,” said Jim. “I got a chance to see a lot more because of him.”

Like many of Butte’s Irish, O’Dwyer ancestors worked the copper mines, not in Butte, but in Allihies.

During his Butte visit, he was more than thrilled when he saw the headframes dotting the landscape on the Butte Hill.

“I am delighted they are being preserved,” he said.

O’Dwyer’s first volume (Eyeries) was printed in 1976, but the books on Allihies, Bere Island, and Castletownbere would come much later, in 1988 and 1989. He would later publish “The Annals of Beara.”

Published in 2009, O’Dwyer’s three volumes were added gems for those trying to gather more information on their Beara ancestors.

According to Crain, in spite of internet resources, these books are invaluable and remain widely used.

“People have come to the Archives from all over — Chicago, New York, Boston, etc., and found their family stories in these books,” she said.

A funeral Mass for Riobard is Saturday at St. Kentigern’s Church in Eyeries. He will be buried at the Gortnabulliga Cemetery, also in Eyeries,

Reflecting on O’Dwyer’s long and distinguished career, Jim Sullivan said that while “Ireland has lost a great man, a great historian, he was a great asset to Butte as well.”