In that era, “Boston politics was a struggle for the spoils of government between the Irish and the Boston Brahmins,” said former US representative Chester G. Atkins. “Joe was a significant part of moving politics beyond that to something that was professionalized, that was governed by rules and fairness, and on delivering services to everybody, not just to certain ethnic groups.”

Mr. Slavet, who also had been the first leader of the anti-poverty agency Action for Boston Community Development, was 104 when he died May 4 in NewBridge on the Charles in Dedham, where he had been living.

As a key Boston official from the late-1940s into the 1960s, Mr. Slavet was “in a lot of ways the last living link to the transition of Boston from James Michael Curley to Hynes” and beyond, said Atkins, who before Congress had served in the Massachusetts House and Senate.

“Joe was in the scrum for a long time and was always respected as being thoughtful,” said Larry DiCara, a former Boston city councilor.

“Looking back, he was fearless, even when he was on a public payroll,” DiCara said. “He let it be known when he thought something was right or something was wrong. Some might have thought of him as a bit of a scold.”

In June 1960, amid what Mr. Slavet called the “frustrating and bitter experiences with the multimillion-dollar Prudential Center and Government Center projects,” he published a detailed and concise essay in The Boston Globe, breaking down why construction was lagging.

“Many of the crises, snarls, and wrangles which have beset the two projects can be attributed to planning pitfalls,” he wrote, detailing everything from an inhospitable tax climate to “the absence of a single city agency staffed by experience professionals to pull all the pieces together, to harmonize conflicting viewpoints, and to keep things moving.”

After his leadership roles with the Boston Municipal Research Bureau and ABCD, Mr. Slavet moved into academia, first at Boston University, where he held a leadership role with the urban affairs department, and then at the University of Massachusetts Boston, where he was a senior fellow at the McCormack Institute.

“He transitioned from a player in government and quasi-government entities to being an academic and was a pioneer in the early academic programs that looked at urban crises,” Atkins said.

In those university roles, “Joe was one of the earliest, and perhaps the earliest and most comprehensive thinker, about what we call today workforce housing,” Atkins said. “A lot of his work on housing is as relevant today as when he wrote it in the ‘70s and ‘80s.”

Born in Boston on March 31, 1920, Joseph S. Slavet was a son of American-born Anna Adelman Slavet, and Dan Slavet.

In a 2007 interview for the Veterans History Project that is in the Library of Congress, Mr. Slavet said his father was born in an area that was then part of Russia, and had arrived in the United States as a teenager. Mr. Slavet said his father had been an apprentice plumber who later worked in a plumbing and hardware supply business.

The older of two brothers, Mr. Slavet graduated from English High School and was a professional musician by his teen years.

“By 15, I was in a jazz band that played in ballrooms throughout New England,” he said in the Veterans History Project oral history.

He said he used his saxophonist income from those regional gigs to pay his way through Boston University, after turning down an offer to join a nationally touring band that would have paid the equivalent of about $3,000 a week in today’s dollars.

While a BU student, he learned that Japan had attacked Pearl Harbor on Dec. 7, 1941. “When I heard that, I turned to my mother and I told her that I think my life has taken another turn,” he recalled.

Serving in the Army, he landed in Normandy, France, seven days into the D-Day invasion. A gunnery officer, he was in charge of 40mm anti-aircraft weapons.

His unit was in Belgium during the Battle of the Bulge. A few months later, the unit discovered a mass grave near a concentration camp.

“This was my first personal experience of what Hitler had done to the Jews,” he said in the oral history.

“Our officers were so enraged,” he recalled, and his unit insisted that because of their complicity with the Nazis, residents of the nearby village should remove the remains of those in the mass grave and give them all proper burials. Among those in the village there was “a lot of handwringing and denying and crying,” he said.

Back home after the war, Mr. Slavet resumed his education. Having graduated with a bachelor’s degree in history from Boston University, he received a master’s in history from BU and a master’s in public administration from Syracuse University.

He also met Muriel Vigor at a dance. They married in 1947 and raised their family in West Roxbury. Mrs. Slavet died in 2011, and Mr. Slavet had lived in the Orchard Cove retirement community in Canton before moving to NewBridge on the Charles.

Staying involved in public policy research long after his colleagues had retired, Mr. Slavet “didn’t stop working,” said his daughter Beth of Washington, D.C. “He always said he did some of his best work in his 80s.”

Mr. Slavet “was generally regarded as the straightest of straight arrows,” DiCara said.

A service has been held for Mr. Slavet, who in addition to Beth leaves two other daughters, Amy Glaser of Easton and Julie of Philadelphia; four grandchildren; seven great-grandchildren.

Mr. Slavet spoke only Yiddish when he started school as a boy, and he delivered his Bar Mitzvah speech in Yiddish. Just before turning 104, he attended his great-grandson’s bris “and he spoke so eloquently there,” Beth said. “He had an incredible life.”

Through his work in public service and academia, Mr. Slavet had a career “that spanned the significant transition of Boston from a city in decline to a city that once again became a city on a hill, and he was a pioneer in the marriage of higher education and municipal policy,” Atkins said.

“To the very end Joe was calling balls and strikes, commenting on politics, calling people out who were self-serving, and praising people who were acting in the public interest.”

Bryan Marquard can be reached at bryan.marquard@globe.com.