CONCORD, N.H. – Former New Hampshire Gov. Walter Peterson who was the state’s chief executive for four years in the late 1960s and early 1970s, has died of lung cancer.

The 88-year-old Peterson, who never smoked, found out he had lung cancer this spring and received treatment at Dartmouth-Hitchcock Medical Center. Peterson, a moderate Republican from Peterborough, was governor from 1969-1973. He lost a bid for re-election after renouncing New Hampshire’s traditional pledge among its political leaders to oppose an income or sales tax.

Peterson’s death was announced Thursday by Gov. John Lynch, who ordered the state’s flags lowered.

Peterson’s son, Andy Peterson, said his father died peacefully at 11 p.m. Wednesday at Monadnock Community Hospital.

“He felt an obligation to the greater world,” said the younger Peterson. “It was just the fact of the matter that was what he was about. He felt strongly it was right to have an investment in the welfare of the town, the state, the nation, the wider world.”

Andy Peterson said his father believed that people working together “are a much greater force than the problems we face.” He said his father knew there was evil in the world, but his real interest was in seeing the good in people grow.

In his statement, Lynch said Peterson was an inspiration, a mentor and a good friend he turned to for advice.

“Governor Walter Peterson represented all that is great and wonderful about our state,” the Democratic governor said in a statement. “With a strength of character as tough as New Hampshire granite, Governor Peterson was a true New Hampshire icon, a gentleman and a strong example of courage and honesty in politics. He never wavered from his principles and always put the needs of people first, which is the mark of a great man and an extraordinary public servant.”

In later years, Peterson warned his party against becoming too extreme. In 2004, he joined other moderate Republicans in calling on President George W. Bush and the Republican party to “come back to the mainstream” on the eve of the Republican National Convention. The group purchased newspaper advertisements, urging the GOP to stop weakening environmental law; start using “pay-as-you-go” budget discipline to end deficits; clear the way for embryonic stem cell research; and appoint mainstream federal judges.

Peterson also served as president of Franklin Pierce College for 20 years and, for a year, as interim president of the University of New Hampshire. He also served in the New Hampshire House in the early 1960s and as its speaker.

“How many times in life can you say you met a really great person? I’ve been in the presence of many great people, but none really compare to Walter,” said state Sen. Lou D’Allesandro, who was a college student when he first met Peterson and later worked with him as vice president of Franklin Pierce University and president of Daniel Webster College.

Both men were huge sports fans and often attended college games together, D’Allesandro said.

Andy Peterson said his father played semi-pro basketball in his 20s, including for the Boston Hobos.

“That is how my mother met him,” he said.

D’Allesandro last visited Peterson on Saturday in the hospital.

“I held his hand, and he gave me that great smile,” said D’Allesandro, D-Manchester. “But he obviously was in pain.”

In 2007, when D’Allesandro and Peterson participated in NPR’s “StoryCorps” project, Peterson was asked who he’d most like to have dinner with. He picked his late father, D’Allesandro recalled.

“Here’s a guy who’s met presidents, met dignitaries all over the world, and the most important person in his life was his father,” the senator said. “He was a giving, amazing guy.”

Born in Nashua, Peterson graduated from Nashua High School and The New Hampton School. He attended William and Mary College and the University of New Hampshire and graduated from Dartmouth College in 1947. He also was a Navy veteran, partner in a real estate business and served as president of the 1974 state constitutional convention.

The state Senate opened its session Thursday with a moment of silence for Peterson, while state and federal politicians from both parties remembered Peterson as a true statesman who put the public good ahead of politics.

“Walter’s passion for public service continued for decades after he left the governor’s office,” said U.S. Sen. Jeanne Shaheen, a Democrat. “His commitment to higher education, in particular, was unparalleled.”

Sen. Kelly Ayotte, a Republican, said she has fond memories of spending time with Peterson in Peterborough. “New Hampshire has lost a dedicated and exceptional public servant with the passing of Gov. Peterson, and all Granite Staters have lost a great friend.”

Republican Rep. Charlie Bass said Peterson made a lasting impact on the state from his time in the Navy to his college president days. “I was fortunate to have known him and to call him my friend,” he said.

Rep. Frank Guinta, also a Republican, noted that as governor, Peterson faced many of the same fiscal issues the state faces today and worked to make government operate more efficiently.

“Governor Peterson’s life was spent in service to the state he loved,” Guinta said.

Former Gov. and U.S. Sen. Judd Gregg said Peterson “brought integrity, a Yankee sense of humor and enormous energy to all his many activities. As a result, his community and state were greatly blessed by his life.”

Peterson married Dorothy Donovan in 1949. He is survived by his wife and their two children, Margaret Petersen and Andrew Peterson.

A small private service for family and friends will be held Wednesday in Peterborough. A memorial service will be held at the Capitol Center for the Arts in Concord on June 12.