Most everyone is familiar with P.T Barnum, Helen Keller and Katharine Hepburn and their links to the Nutmeg State.

But fewer people know the Connecticut connection to the country’s first black ambassador, a workplace safety pioneer, and the third U.S. Supreme Court chief justice.

In his new book Connecticut Vanguards: Historic Trailblazers & Their Legacies, author Eric D. Lehman describes the lives and contributions of 24 people — most well-known, but not all — who lived or worked in the state.

They vary from Revolutionary War leaders to inventors, artists to doctors, and educators to a chef. In their own way, all changed the world through their intellect, hard work, ambition, and perseverance.

“The fun part is why these people changed their field,” Lehman, a University of Bridgeport English professor, said during a recent interview. “Some actually invented their whole field, like Frederick Law Olmsted with landscape architecture.”

Helen Keller, who spent her final decades in Easton, is famous for overcoming blindness and deafness to highlight the potential of people with disabilities. But Keller also fought for social justice, taking on racism, pushing for prison reform, and helping found the American Civil Liberties Union. “She invented modern advocacy,” Lehman said.

Choosing 24 people from diverse fields and eras to highlight was not easy. “There was a process of elimination,” he said. “Why not Mark Twain instead of Harriet Beecher Stowe? Why not Paul Newman instead of Katharine Hepburn?”

Lehman explained why he selected Stowe instead of Twain, perhaps the most famous Connecticut resident not profiled, when picking a novelist to include. The authors were neighbors in Hartford in the mid-1800s.

“Mark Twain had greater impact on literature, but Harriet Beecher Stowe’s novel had more impact beyond literature than Twain,” he said, referring to how the publication of Uncle Tom’s Cabin in 1852 changed people’s views on slavery leading up to the Civil War.

Connecticut Vanguards features short profiles of the individuals and their contributions as well as photos. Lehman’s 13th book, it was published in March by The History Press and is available at local bookstores and online.

The Hamden resident suggested the concept to the publisher. “I wanted to do a series of short biographies of people who’ve succeeded or changed human endeavor,” he said.

Writing the book required a lot of research. Lehman estimated he read 75 books on his subjects, plus plenty of other material. “I wanted a few different perspectives of each person,” he said.

He was quite familiar with a few of the people from his past work, but others he’d never heard of before, such as Ebenezer Bassett and Alice Hamilton. Friends suggested both for inclusion.

Bassett was a Litchfield native and professor who was appointed ambassador to Haiti by President Ulysses S. Grant in 1869, becoming the first African-American to hold such a post.

Hamilton, of East Haddam, was the first woman professor at Harvard and worked to make factories safe for workers, bringing prominence to occupational medicine in the early 1900s.

Two individuals in the book are still alive. Bun Lai, a New Haven-based chef whose seafood culinary innovations have changed the restaurant business, and Dr. Henry Lee, the forensic scientist who headed the state crime lab. Lehman spoke directly with both of them.

Most of the people profiled faced serious challenges in their lives. They overcame debt, illness, family deaths, and public opposition. They had, according to the book, “an ability to deal with failure, sometimes over and over again.”

Such was the case with Charles Goodyear, who grew up in Naugatuck and is known for inventing the vulcanization of rubber in the 1840s. “He suffered tremendous poverty and physical damage from his chemistry,” Lehman said. “His whole life he was miserable.”

Eli Whitney of New Haven is famous for inventing the cotton gin, but patent infringement brought him to the edge of financial ruin. Then he went into the gun business and became wealthy.

Bridgeport’s P.T. Barnum went bankrupt, his house and museums burned down, and he wasn’t a very nice person when younger, Lehman said. He was a drinker, casual racist like many of his white contemporaries, didn’t care about his performers, and fixated on making money.

“He worked through that and redeemed himself,” said Lehman, pointing out that Barnum became a teetotaler, abolitionist, Abraham Lincoln supporter, and better family man.

Playwright and New London summer resident Eugene O’Neill was successful, winning Pulitzer Prizes and a Nobel Prize, but he was an unhappy man and an alcoholic with a tortured family life.

“How do we reconcile that with our ideas of success and the American Dream?” Lehman asked. “It shows you can reach the pinnacle of your field and be at the bottom of a bottle.”

Perhaps the biggest surprise to Lehman was the differences among his subjects. “There are many roads to success and changing the world,” he said. “No one seemed to have the same personality — all were unique. Some were jerks, some nice people. Some were on the edge on insanity. I found it remarkable there isn’t one formula.”

One of the lesser known figures in the book is Oliver Ellsworth, who nonetheless helped draft the Constitution and create the federal court system, and served as a U.S. Supreme Court chief justice, senator and ambassador.

“He’s one I was particularly happy to put in the book, because I wanted to say, ‘Hey, this guy is from Connecticut!’” Lehman said. “No one really knows about him here unless you’ve been to his house in Windsor.”

He hopes the book helps people feel proud of their home state. “These are our neighbors,” Lehman said. “We should know who they are and celebrate their achievements.”