Roberta McCain, an independent-minded oil heiress who was married to one of the Navy’s highest-ranking officers and who displayed characteristic pluck when she took to the presidential campaign trail at age 96 on behalf of her son, Sen. John McCain of Arizona, died Oct. 12 at her home in Washington. She was 108.

Her daughter-in-law Cindy McCain announced the death in a tweet on Monday but did not provide further details. Cindy McCain’s husband, John, died in August 2018 of brain cancer.

Mrs. McCain was the gregarious and stylish center of gravity for her family, which was near the center of American military and political power for more than a half-century. Her father-in-law, John S. McCain Sr., a four-star Navy admiral, commanded forces in the Pacific during World War II; her husband, John S. McCain Jr., another four-star Navy admiral, led the U.S. invasion of the Dominican Republic in 1965 and commanded U.S. forces in the Pacific during the Vietnam War.

She raised three children and turned her home on Capitol Hill into a cocktail-hour salon for prominent lawmakers, aiding her husband’s climb through the Navy ranks. She was known to make breakfast for politicians who were key to her husband’s success. Her friends included the British military leader and statesman Louis Mountbatten, the oil tycoon J. Paul Getty, and American writer and ambassador Clare Boothe Luce.

In 1967, she and her husband were in London preparing for a dinner party at the home of the Iranian ambassador when they learned that their son John, a Navy pilot in the Vietnam War, had been shot down over Hanoi. The ­McCains went on with the dinner, sharing the news with no one.

A week later, Mrs. McCain sent a letter to President Lyndon B. Johnson.

“As the parent of a son who was shot down in Hanoi last week and is now a prisoner of war, I wonder if you are interested to know that both my husband and I back you and your policies 100 percent in Vietnam,” she wrote. “One reads so much of other opinions, that I just hope that you and the people really making the sacrifice believe in our country and in you. May God bless you and keep you strong in your courage and convictions.”

John McCain III endured isolation and torture for the next 51/years as a prisoner of war in North Vietnam. Mrs. McCain, who could only wonder about her son’s mental and physical condition, remained stoic.

“When Johnny was in prison, that woman never made a peep,” Rowena Willis, Mrs. McCain’s identical twin, told Vogue magazine in 2008.

Mrs. McCain did not emerge as a public figure until her son sought the Republican nomination for president in 2000, the first of his two unsuccessful bids for the White House. She largely ignored that campaign, later saying with typical frankness that she “never expected him to get elected, and didn’t care if he was. I didn’t think he had enough money, enough expertise, enough anything.”

Eight years later, she had changed her mind about her son’s prospects and was much more involved as he won the Republican nomination for president.

She was, to the dismay of some of her son’s handlers, the straightest-talking member of candidate McCain’s “Straight Talk Express.”

In a widely publicized 2008 interview, she said Republicans unhappy with her son’s independent streak would have to “hold their noses” and vote for him. What about her son’s support from his party’s conservative base? “I don’t think he has any,” she said.

Campaign operatives kept Mrs. McCain away from reporters during the remaining months of the presidential race, lest she say something else inconveniently honest. She continued to appear at campaign rallies, however, drawing crowds with her snow-white hair, two-inch heels and brassy reputation.

When John McCain’s critics questioned whether he was too old to serve as president — he was 72 on Election Day 2008 — he simply introduced them to his mother.

'Defies Family'

Roberta Wright was born Feb. 7, 1912, in Muskogee, Okla., where her father, Archibald, bought vast tracts of land just before the oil boom. Awash in wealth, he retired young and moved his family to Los Angeles when Roberta was 12.

She got her taste for travel from her dad, who took his brood on automobile journeys for weeks on end, from the Great Lakes to the Mojave Desert.

“He took us somewhere every summer for the month of August,” she told the New York Times in 2007. “We’d go to a lake in Minnesota, and once he took us to see the source of the Mississippi. It was the littlest trickle you ever saw.”

When Roberta was a freshman at the University of Southern California, she met Jack McCain, a young Navy officer who was serving aboard a battleship with its home port at Long Beach. Against the wishes of her mother, who disapproved of the match, the pair eloped to Tijuana, Mexico. They were married above a bar named Caesar’s.

“Society Coed Elopes With Navy Officer: Roberta Wright Defies Family,” read the headline in the San Francisco Examiner.

“I realize now I was so immature. I just took life as it came — still do,” she told Vogue in 2008.

After 48 years of marriage, her husband had a heart attack on a transatlantic flight home to Washington and died. Her daughter, Jean Alexandra “Sandy” Morgan, died in 2019. Survivors include a son, Joseph P. McCain of Washington; 10 grandchildren; 11 great-grandchildren; and seven great-great-grandchildren.

A spin in the Benz

After the death of her husband in 1981, she and her twin (who died in 2011) spent months each year traveling the world. When they could not find a car-rental agency willing to rent to a pair of women in their late 80s, they bought one — a Mercedes “baby Benz” that they drove from Munich to Kazakhstan and Uzbekistan.

“I wanted to see Samarkand,” Mrs. McCain said by way of explanation.

She kept the car in Europe until 2006, when she shipped it home to Washington. Then she drove solo across the country to deliver the car to a great-nephew in San Francisco. Along the way, she picked up a speeding ticket for driving 112 miles an hour in northern Arizona.

“She was a willful, rebellious girl,” John McCain wrote in his 1999 memoir, “Faith of My Fathers.”

In her 90s, Mrs. McCain spent three hours each Tuesday morning at the National Gallery of Art or the Freer Gallery of Art, whose collection of Chinese porcelain she particularly admired. Asked by Vogue to explain her longevity, good health and general fearlessness, she shrugged.

“I don’t do anything I’m supposed to do. I don’t exercise and today, I’ve already eaten a half a box of caramel popcorn,” she told the magazine. “Honey, I’ve had a dream life, and it was all luck.”

Correction: The top photo caption previously misstated the rank of Roberta McCain’s son. At the time, John S. McCain III was a lieutenant junior grade and not a lieutenant.