In the final years of the Roaring Twenties, Joseph P. Kennedy, patriarch of what would become known as “America’s royal family,” purchased a white clapboard house in Hyannis Port, a picturesque village on Cape Cod.

Joe renovated the place — which boasted a breathtaking view of Nantucket Sound — for his wife, Rose, the Kennedy matriarch, and their nine children.

It would soon become ground zero as the world-famous Kennedy Compound, the summer playground for the Kennedys, from John “Jack” and Jackie, to Bobby and Ethel and their kids, and other members of the Boston clan who would purchase adjoining homes.

“This house has been the shelter, the walls behind which the family grieved, laughed, exhaled,” writes Kate Storey in “White House by the Sea: A Century of the Kennedys at Hyannis Port,” (Scribner).

“It is the heart of the Kennedy Compound suspended somewhere between the past and the present.”

The house would soon be expanded by Joe Kennedy — a movie producer, political wheeler-dealer, purported Prohibition rum runner, and future U.S. ambassador to Great Britain — into a stately mansion of 21 rooms, including 12 bedrooms, a steam room, and even a basement theater.

And then a tall fence went up — a privacy stockade affair that kept out peering eyes.

According to Storey, Rose had no interest in entertaining or socializing with the neighbors, who viewed the Kennedys as “new-money Irish.”

Instead, the family closed ranks to share their lives over summers and holidays for more than one hundred years, sailing, playing touch football — which they made a virtual national sport — and where board games were played and analyzed along with political schemes.

The adults drank “creamy daiquiris,” the patriarch’s favorite mix.

It’s here that First Lady Jackie Kennedy taught other Kennedys to dance the Twist, the Chubby Checker hit and craze that began in the early years of her husband Jack’s ill-fated presidency.

And it’s where Jackie’s mother-in-law, Rose, savored watching Teddy, her fourth son, the future “Lion of the Senate,” do the dance.

“He is so big and has such a big derriere it is funny to see him throw himself around,” Rose wrote in her diary, according to Storey.

And when Rose played “Sweet Adeline,” a barbershop standard from the early 1900s on the piano in the living room, it was a signal to everyone that dinner was ready.

For the matriarch, the house on Marchant Avenue was life at its best.

Rose saw it as “a golden interval” with Joe spending more time with his children — checking the kids for clean fingernails in the morning and as a coach pointing out what they were doing wrong in sports, even following behind them in a motorboat while they were learning to sail and shouting out their mistakes.

But just as there was plenty of joy celebrated within the walls of the house, there was also sadness.

The third Kennedy child, Rosemary, was born in 1918.

At birth, a nurse held Rose’s legs together and pushed the baby Rosemary back into the birth canal while waiting for the doctor, late to arrive, by two hours.

When Rosemary was 23 and still exhibiting temperamental mood changes traced back to her birth, Joe would unilaterally decide that she have a prefrontal lobotomy, a radical experimental procedure in 1941.

The lobotomy procedure was a failure and Rosemary would be hidden away in a Catholic institution in Wisconsin.

“She simply vanished,” writes Storey — until the years following Joe’s death in 1969.

Rose sent for her daughter to join the family on the Cape in 1975.

Rosemary died in 2005, at age 86.

Along with the tragedy of Rosemary was the scandal surrounding Joe’s affair with Hollywood’s reigning silent film sex goddess Gloria Swanson.

While Rose was off on European shopping excursions, Swanson would arrive at the compound in her chauffeur-driven Duesenberg, igniting gossip around town.

(Rose herself would later confess to a friend that she had had her own “indiscretions” and showed them exquisite jewelry she had been gifted, supposedly by lovers, writes the author.)

After the Swanson affair ended, Joe was often seen on walks with his pretty secretary, Janet DesRosiers.

DesRosiers would later reveal to author Ronald Kessler in the 2015 book “The Sins of the Father: Joseph P. Kennedy and the Dynasty He Founded” that she was a virgin before being seduced by the Kennedy patriarch, who was “well-endowed,” saying that they made love daily. (“The lovemaking went on for hours,” she told Kessler. “There was joy and ecstasy and laughter and giggles, eating chocolate cake and drinking milk at midnight in the kitchen.”)

That affair lasted ten years before DesRosiers moved on to become a secretary on Jack Kennedy’s presidential plane, accommodating JFK by massaging his feet and hands in private.

Summers meant endless parties at the Kennedy compound with visiting stars from Hollywood.

When Jackie was alone in Hyannis Port, she knew of Jack’s many indiscretions taking place in Washington, DC, writes Storey, and viewed his appeal to women as his “incandescence.” (Her nickname for him was “Magic.”)

But after suffering a miscarriage in 1955, she confided to her sister, Lee Radziwill, that the “magic” was gone.

The magic also changed within the compound with Joe Kennedy’s stroke in 1961 that left him partially paralyzed and unable to speak.

Summers became steeped in grief with the assassinations of Jack in 1963, Bobby in 1968, and Joe Kennedy’s earlier stroke from a blood clot in his brain in 1961.

It left him partially paralyzed and unable to speak.

He died in 1969.

Still, it was in Hyannis that Jackie would experience new love in the years after JFK’s assassination.

Greek shipping magnate Aristotle Onassis would visit the widowed former First Lady in Hyannis Port bringing Greek gifts of feta cheese and cartons of her favorite cigarettes.

“She romanced Onassis right on the street in front of my house,” a Hyannis Port neighbor told Storey. “They used to have a champagne lunch here and then they would go dancing up the hill in front of my house and then go whistling down the street to their house. And I just kept asking myself, ‘How in God’s name could she love that guy?’ ”

They married in 1968 and divorced seven years later.

While Jackie’s house was peaceful and hadn’t changed since the two-story clapboard house — located directly behind the patriarch’s place — was purchased in 1957 for $45,948, her sister-in-law Ethel’s was “loud and full of life” — and involved plenty of troubled teen antics.

At the end of the summer of 1970, Bobby Jr., then 16, was hanging with the Hyannis Port Terrors, local teenagers who broke into houses stealing booze and phones, smoking pot, hiding in bushes, and terrorizing neighbors by shooting off BB guns in town.

Bobby was arrested for spitting ice cream in the face of a cop and had to be bailed out by his cousin, Bobby Shriver.

Jackie’s secretary had discovered that the Kennedy cousins were growing marijuana among the flowers in Rose’s beautiful gardens, which had been designed by Frederick Law Olmsted, who designed New York’s Central Park.

Sick of these antics, Ethel locked her sons out of the house.

Bobby Jr’s cousin, John F. Kennedy Jr. — who would be voted People magazine’s “sexiest man alive” in 1988 — viewed life at the compound as heavenly, and would often bring his future wife, Carolyn Bessette, there.

Carolyn loved the place, where she would cook dinner in bare feet, pajama pants, and one of John’s old shirts, according to Storey. 

It ended horribly for the famous couple when JFK Jr.’s plane went down in the Atlantic Ocean off Martha’s Vineyard on July 16, 1999.

In August 2014, the Kennedy family and friends celebrated the 3^rd marriage of RFK Jr., now a candidate for the presidency, to the actress Cheryl Hines.

Life goes on behind that high fence in front of the Compound.

Over one hundred and five Kennedy children, great-grandchildren, and great-great-grandchildren have called it their summer home.